dialyzer_dataflow: Add map support

21 files changed, 3109 insertions, 15 deletions

diff --git a/lib/dialyzer/src/dialyzer.erl b/lib/dialyzer/src/dialyzer.erl
index 9f51dfe356..bcac8afe64 100644
--- a/lib/dialyzer/src/dialyzer.erl
+++ b/lib/dialyzer/src/dialyzer.erl
@@ -336,6 +336,9 @@ message_to_string({guard_fail, []}) ->
   "Clause guard cannot succeed.\n";
 message_to_string({guard_fail, [Arg1, Infix, Arg2]}) ->
   io_lib:format("Guard test ~s ~s ~s can never succeed\n", [Arg1, Infix, Arg2]);
+message_to_string({map_update, [Type, Key]}) ->
+  io_lib:format("A key of type ~s cannot exist "
+		"in a map of type ~s\n", [Key, Type]);
 message_to_string({neg_guard_fail, [Arg1, Infix, Arg2]}) ->
   io_lib:format("Guard test not(~s ~s ~s) can never succeed\n",
 		[Arg1, Infix, Arg2]);
diff --git a/lib/dialyzer/src/dialyzer.hrl b/lib/dialyzer/src/dialyzer.hrl
index 601e2e954b..ea6a71217c 100644
--- a/lib/dialyzer/src/dialyzer.hrl
+++ b/lib/dialyzer/src/dialyzer.hrl
@@ -60,6 +60,7 @@
 -define(WARN_BEHAVIOUR, warn_behaviour).
 -define(WARN_UNDEFINED_CALLBACK, warn_undefined_callbacks).
 -define(WARN_UNKNOWN, warn_unknown).
+-define(WARN_MAP_CONSTRUCTION, warn_map_construction).
 
 %%
 %% The following type has double role:
@@ -75,7 +76,8 @@
                        | ?WARN_CONTRACT_SUPERTYPE | ?WARN_CALLGRAPH
                        | ?WARN_UNMATCHED_RETURN | ?WARN_RACE_CONDITION
                        | ?WARN_BEHAVIOUR | ?WARN_CONTRACT_RANGE
-		       | ?WARN_UNDEFINED_CALLBACK | ?WARN_UNKNOWN.
+		       | ?WARN_UNDEFINED_CALLBACK | ?WARN_UNKNOWN
+		       | ?WARN_MAP_CONSTRUCTION.
 
 %%
 %% This is the representation of each warning as they will be returned
diff --git a/lib/dialyzer/src/dialyzer_dataflow.erl b/lib/dialyzer/src/dialyzer_dataflow.erl
index 48eaf8510b..a3b3e3291c 100644
--- a/lib/dialyzer/src/dialyzer_dataflow.erl
+++ b/lib/dialyzer/src/dialyzer_dataflow.erl
@@ -72,7 +72,7 @@
 	 t_tuple/0, t_tuple/1, t_tuple_args/1, t_tuple_args/2,
          t_tuple_subtypes/2,
 	 t_unit/0, t_unopaque/2,
-	 t_map/1
+	 t_map/0, t_map/1, t_is_singleton/2
      ]).
 
 %%-define(DEBUG, true).
@@ -342,8 +342,6 @@ traverse(Tree, Map, State) ->
       handle_tuple(Tree, Map, State);
     map ->
       handle_map(Tree, Map, State);
-    map_pair ->
-      handle_map_pair(Tree, Map, State);
     values ->
       Elements = cerl:values_es(Tree),
       {State1, Map1, EsType} = traverse_list(Elements, Map, State),
@@ -1102,15 +1100,54 @@ handle_try(Tree, Map, State) ->
 %%----------------------------------------
 
 handle_map(Tree,Map,State) ->
-    Pairs = cerl:map_es(Tree),
-    {State1, Map1, TypePairs} = traverse_list(Pairs,Map,State),
-    {State1, Map1, t_map(TypePairs)}.
+  Pairs = cerl:map_es(Tree),
+  Arg = cerl:map_arg(Tree),
+  {State1, Map1, ArgType} = traverse(Arg, Map, State),
+  ArgType1 = t_inf(t_map(), ArgType),
+  case t_is_none_or_unit(ArgType1) of
+    true ->
+      {State1, Map1, ArgType1};
+    false ->
+      {State2, Map2, TypePairs, ExactKeys} =
+	traverse_map_pairs(Pairs, Map1, State1, t_none(), [], []),
+      InsertPair = fun({KV,assoc,_},Acc) -> erl_types:t_map_put(KV,Acc);
+		      ({KV,exact,KVTree},Acc) ->
+		       case t_is_none(T=erl_types:t_map_update(KV,Acc)) of
+			 true -> throw({none, Acc, KV, KVTree});
+			 false -> T
+		       end
+		   end,
+      try lists:foldl(InsertPair, ArgType1, TypePairs)
+      of ResT ->
+	  BindT = t_map([{K, t_any()} || K <- ExactKeys]),
+	  case bind_pat_vars_reverse([Arg], [BindT], [], Map2, State2) of
+	    {error, _, _, _, _} -> {State2, Map2, ResT};
+	    {Map3, _} ->           {State2, Map3, ResT}
+	  end
+      catch {none, MapType, {K,_}, KVTree} ->
+	  Msg2 = {map_update, [format_type(MapType, State2),
+			       format_type(K, State2)]},
+	  {state__add_warning(State2, ?WARN_MAP_CONSTRUCTION, KVTree, Msg2),
+	   Map2, t_none()}
+      end
+  end.
 
-handle_map_pair(Tree,Map,State) ->
-  Key = cerl:map_pair_key(Tree),
-  Val = cerl:map_pair_val(Tree),
+traverse_map_pairs([], Map, State, _ShadowKeys, PairAcc, KeyAcc) ->
+  {State, Map, lists:reverse(PairAcc), KeyAcc};
+traverse_map_pairs([Pair|Pairs], Map, State, ShadowKeys, PairAcc, KeyAcc) ->
+  Key = cerl:map_pair_key(Pair),
+  Val = cerl:map_pair_val(Pair),
+  Op = cerl:map_pair_op(Pair),
   {State1, Map1, [K,V]} = traverse_list([Key,Val],Map,State),
-  {State1, Map1, {K,V}}.
+  KeyAcc1 =
+    case cerl:is_literal(Op) andalso cerl:concrete(Op) =:= exact andalso
+      t_is_singleton(K, State#state.opaques) andalso
+      t_is_none(t_inf(ShadowKeys, K)) of
+      true -> [K|KeyAcc];
+      false -> KeyAcc
+  end,
+  traverse_map_pairs(Pairs, Map1, State1, t_sup(K, ShadowKeys),
+		     [{{K,V},cerl:concrete(Op),Pair}|PairAcc], KeyAcc1).
 
 %%----------------------------------------
 
@@ -1493,7 +1530,43 @@ bind_pat_vars([Pat|PatLeft], [Type|TypeLeft], Acc, Map, State, Rev) ->
 	  false -> {Map, Literal}
 	end;
       map ->
-	  {Map, t_map([])};
+	MapT = t_inf(Type, t_map(), Opaques),
+	case t_is_none(MapT) of
+	  true ->
+	    bind_opaque_pats(t_map(), Type, Pat, State);
+	  false ->
+	    case Rev of
+	      %% TODO: Reverse matching (propagating a matched subset back to a value)
+	      true -> {Map, MapT};
+	      false ->
+		FoldFun =
+		  fun(Pair, {MapAcc, ListAcc}) ->
+		      %% Only exact (:=) can appear in patterns
+		      exact = cerl:concrete(cerl:map_pair_op(Pair)),
+		      Key = cerl:map_pair_key(Pair),
+		      KeyType =
+			case cerl:type(Key) of
+			  var ->
+			    case state__lookup_type_for_letrec(Key, State) of
+			      error -> lookup_type(Key, MapAcc);
+			      {ok, RecType} -> RecType
+			    end;
+			  literal ->
+			    literal_type(Key)
+			end,
+		      Bind = erl_types:t_map_get(KeyType, MapT),
+		      {MapAcc1, [ValType]} =
+			bind_pat_vars([cerl:map_pair_val(Pair)],
+				      [Bind], [], MapAcc, State, Rev),
+		      case t_is_singleton(KeyType, Opaques) of
+			true  -> {MapAcc1, [{KeyType, ValType}|ListAcc]};
+			false -> {MapAcc1, ListAcc}
+		      end
+		  end,
+		{Map1, Pairs} = lists:foldl(FoldFun, {Map, []}, cerl:map_es(Pat)),
+		{Map1, t_inf(MapT, t_map(Pairs))}
+	    end
+	end;
       tuple ->
 	Es = cerl:tuple_es(Pat),
 	{TypedRecord, Prototype} =
@@ -1718,7 +1791,10 @@ bind_guard(Guard, Map, Env, Eval, State) ->
       {Map1, Es} = bind_guard_list(Es0, Map, Env, dont_know, State),
       {Map1, t_tuple(Es)};
     map ->
-      {Map, t_map([])};
+      case Eval of
+	dont_know -> handle_guard_map(Guard, Map, Env, State);
+	_PosOrNeg -> {Map, t_none()}  %% Map exprs do not produce bools
+      end;
     'let' ->
       Arg = cerl:let_arg(Guard),
       [Var] = cerl:let_vars(Guard),
@@ -1761,7 +1837,7 @@ handle_guard_call(Guard, Map, Env, Eval, State) ->
     {erlang, F, 1} when F =:= is_atom; F =:= is_boolean;
 			F =:= is_binary; F =:= is_bitstring;
 			F =:= is_float; F =:= is_function;
-			F =:= is_integer; F =:= is_list;
+			F =:= is_integer; F =:= is_list; F =:= is_map;
 			F =:= is_number; F =:= is_pid; F =:= is_port;
 			F =:= is_reference; F =:= is_tuple ->
       handle_guard_type_test(Guard, F, Map, Env, Eval, State);
@@ -1841,6 +1917,7 @@ bind_type_test(Eval, TypeTest, ArgType, State) ->
 	   is_function -> t_fun();
 	   is_integer -> t_integer();
 	   is_list -> t_maybe_improper_list();
+	   is_map -> t_map();
 	   is_number -> t_number();
 	   is_pid -> t_pid();
 	   is_port -> t_port();
@@ -2349,6 +2426,30 @@ bind_guard_list([G|Gs], Map, Env, Eval, State, Acc) ->
 bind_guard_list([], Map, _Env, _Eval, _State, Acc) ->
   {Map, lists:reverse(Acc)}.
 
+handle_guard_map(Guard, Map, Env, State) ->
+  Pairs = cerl:map_es(Guard),
+  Arg = cerl:map_arg(Guard),
+  {Map1, ArgType0} = bind_guard(Arg, Map, Env, dont_know, State),
+  ArgType1 = t_inf(t_map(), ArgType0),
+  case t_is_none_or_unit(ArgType1) of
+    true -> {Map1, t_none()};
+    false ->
+      {Map2, TypePairs} = bind_guard_map_pairs(Pairs, Map1, Env, State, []),
+      {Map2, lists:foldl(fun({KV,assoc},Acc) -> erl_types:t_map_put(KV,Acc);
+			    ({KV,exact},Acc) -> erl_types:t_map_update(KV,Acc)
+			 end, ArgType1, TypePairs)}
+  end.
+
+bind_guard_map_pairs([], Map, _Env, _State, PairAcc) ->
+  {Map, lists:reverse(PairAcc)};
+bind_guard_map_pairs([Pair|Pairs], Map, Env, State, PairAcc) ->
+  Key = cerl:map_pair_key(Pair),
+  Val = cerl:map_pair_val(Pair),
+  Op = cerl:map_pair_op(Pair),
+  {Map1, [K,V]} = bind_guard_list([Key,Val],Map,Env,dont_know,State),
+  bind_guard_map_pairs(Pairs, Map1, Env, State,
+		       [{{K,V},cerl:concrete(Op)}|PairAcc]).
+
 -type eval() :: 'pos' | 'neg' | 'dont_know'.
 
 -spec signal_guard_fail(eval(), cerl:c_call(), [type()],
@@ -2705,6 +2806,9 @@ mark_as_fresh([Tree|Left], Map) ->
       bitstr ->
 	%% The Size field is not fresh.
 	{SubTrees1 -- [cerl:bitstr_size(Tree)], Map};
+      map_pair ->
+	%% The keys are not fresh
+	{SubTrees1 -- [cerl:map_pair_key(Tree)], Map};
       var ->
 	{SubTrees1, enter_type(Tree, t_any(), Map)};
       _ ->
diff --git a/lib/dialyzer/src/dialyzer_options.erl b/lib/dialyzer/src/dialyzer_options.erl
index dd81dd01ed..add660eae9 100644
--- a/lib/dialyzer/src/dialyzer_options.erl
+++ b/lib/dialyzer/src/dialyzer_options.erl
@@ -47,6 +47,7 @@ build(Opts) ->
 		  ?WARN_CALLGRAPH,
 		  ?WARN_FAILING_CALL,
 		  ?WARN_BIN_CONSTRUCTION,
+		  ?WARN_MAP_CONSTRUCTION,
 		  ?WARN_CONTRACT_RANGE,
 		  ?WARN_CONTRACT_TYPES,
 		  ?WARN_CONTRACT_SYNTAX,
diff --git a/lib/dialyzer/test/map_SUITE_data/results/bad_argument b/lib/dialyzer/test/map_SUITE_data/results/bad_argument
index 8d76ae5e3f..af61a89638 100644
--- a/lib/dialyzer/test/map_SUITE_data/results/bad_argument
+++ b/lib/dialyzer/test/map_SUITE_data/results/bad_argument
@@ -2,3 +2,4 @@
 bad_argument.erl:14: Function t3/0 has no local return
 bad_argument.erl:15: Guard test is_map('not_a_map') can never succeed
 bad_argument.erl:5: Function t/0 has no local return
+bad_argument.erl:6: A key of type 'b' cannot exist in a map of type #{'a':='q'}
diff --git a/lib/dialyzer/test/map_SUITE_data/results/exact b/lib/dialyzer/test/map_SUITE_data/results/exact
new file mode 100644
index 0000000000..03090e5803
--- /dev/null
+++ b/lib/dialyzer/test/map_SUITE_data/results/exact
@@ -0,0 +1,6 @@
+
+exact.erl:15: Function t2/1 has no local return
+exact.erl:16: The call exact:has_a(M::#{}) will never return since it differs in the 1st argument from the success typing arguments: (#{'a':=_, ...})
+exact.erl:22: Function has_a/1 has no local return
+exact.erl:23: A key of type 'a' cannot exist in a map of type #{}
+exact.erl:8: The pattern ~{'a':=_}~ can never match the type #{}
diff --git a/lib/dialyzer/test/map_SUITE_data/results/guard_update b/lib/dialyzer/test/map_SUITE_data/results/guard_update
new file mode 100644
index 0000000000..f6200ae2af
--- /dev/null
+++ b/lib/dialyzer/test/map_SUITE_data/results/guard_update
@@ -0,0 +1,8 @@
+
+guard_update.erl:12: Function t2/0 has no local return
+guard_update.erl:15: Clause guard cannot succeed. The variable M was matched against the type #{'a':=2}
+guard_update.erl:15: Function f2/1 has no local return
+guard_update.erl:5: Function t/0 has no local return
+guard_update.erl:6: The call guard_update:f(#{'a':=2}) will never return since it differs in the 1st argument from the success typing arguments: (#{'b':=_, ...})
+guard_update.erl:8: Clause guard cannot succeed. The variable M was matched against the type #{'a':=2}
+guard_update.erl:8: Function f/1 has no local return
diff --git a/lib/dialyzer/test/map_SUITE_data/results/initial_dataflow b/lib/dialyzer/test/map_SUITE_data/results/initial_dataflow
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/lib/dialyzer/test/map_SUITE_data/results/initial_dataflow
diff --git a/lib/dialyzer/test/map_SUITE_data/results/map_galore b/lib/dialyzer/test/map_SUITE_data/results/map_galore
new file mode 100644
index 0000000000..08c99e0c9a
--- /dev/null
+++ b/lib/dialyzer/test/map_SUITE_data/results/map_galore
@@ -0,0 +1,36 @@
+
+map_galore.erl:1000: A key of type 42 cannot exist in a map of type #{1:='a', 2:='b', 4:='d', 5:='e', float()=>'c' | 'v'}
+map_galore.erl:1080: A key of type 'nonexisting' cannot exist in a map of type #{#{'map':='key', 'one':='small'}:=[32 | 49 | 97 | 101 | 107 | 108 | 109 | 112 | 115 | 121,...], #{'map':='key', 'second':='small'}:=[32 | 50 | 97 | 101 | 107 | 108 | 109 | 112 | 115 | 121,...], #{'map':='key', 'third':='small'}:=[32 | 51 | 97 | 101 | 107 | 108 | 109 | 112 | 115 | 121,...], 10:='a0', 11:='a1', 12:='a2', 13:='a3', 14:='a4', 15:='a5', 16:='a6', 17:='a7', 18:='a8', 19:='a9', 20:='b0', 21:='b1', 22:='b2', 23:='b3', 24:='b4', 25:='b5', 26:='b6', 27:='b7', 28:='b8', 29:='b9', 30:=[48 | 99,...], 31:=[49 | 99,...], 32:=[50 | 99,...], 33:=[51 | 99,...], 34:=[52 | 99,...], 35:=[53 | 99,...], 36:=[54 | 99,...], 37:=[55 | 99,...], 38:=[56 | 99,...], 39:=[57 | 99,...], <<_:16>> | [48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57,...] | float() | {[[48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57,...],...]} | #{10:='a0', 11:='a1', 12:='a2', 13:='a3', 14:='a4', 15:='a5', 17:='a7', 18:='a8', 19:='a9', 20:='b0', 21:='b1', 22:='b2', 23:='b3', 24:='b4', 25:='b5', 27:='b7', 28:='b8', 29:='b9', 30:=[48 | 99,...], 31:=[49 | 99,...], 32:=[50 | 99,...], 33:=[51 | 99,...], 34:=[52 | 99,...], 35:=[53 | 99,...], 37:=[55 | 99,...], 38:=[56 | 99,...], 39:=[57 | 99,...], 'k16'=>'a6', 'k26'=>'b6', 'k36'=>[54 | 99,...], 16=>'a6', 26=>'b6', 36=>[54 | 99,...], <<_:16>> | [48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57,...] | {[[48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57,...],...]}=>[48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57 | 100 | 101,...]}=>atom() | [1..255,...]}
+map_galore.erl:1082: A key of type 42 cannot exist in a map of type #{#{'map':='key', 'one':='small'}:=[32 | 49 | 97 | 101 | 107 | 108 | 109 | 112 | 115 | 121,...], #{'map':='key', 'second':='small'}:=[32 | 50 | 97 | 101 | 107 | 108 | 109 | 112 | 115 | 121,...], #{'map':='key', 'third':='small'}:=[32 | 51 | 97 | 101 | 107 | 108 | 109 | 112 | 115 | 121,...], 10:='a0', 11:='a1', 12:='a2', 13:='a3', 14:='a4', 15:='a5', 16:='a6', 17:='a7', 18:='a8', 19:='a9', 20:='b0', 21:='b1', 22:='b2', 23:='b3', 24:='b4', 25:='b5', 26:='b6', 27:='b7', 28:='b8', 29:='b9', 30:=[48 | 99,...], 31:=[49 | 99,...], 32:=[50 | 99,...], 33:=[51 | 99,...], 34:=[52 | 99,...], 35:=[53 | 99,...], 36:=[54 | 99,...], 37:=[55 | 99,...], 38:=[56 | 99,...], 39:=[57 | 99,...], <<_:16>> | [48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57,...] | float() | {[[48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57,...],...]} | #{10:='a0', 11:='a1', 12:='a2', 13:='a3', 14:='a4', 15:='a5', 17:='a7', 18:='a8', 19:='a9', 20:='b0', 21:='b1', 22:='b2', 23:='b3', 24:='b4', 25:='b5', 27:='b7', 28:='b8', 29:='b9', 30:=[48 | 99,...], 31:=[49 | 99,...], 32:=[50 | 99,...], 33:=[51 | 99,...], 34:=[52 | 99,...], 35:=[53 | 99,...], 37:=[55 | 99,...], 38:=[56 | 99,...], 39:=[57 | 99,...], 'k16'=>'a6', 'k26'=>'b6', 'k36'=>[54 | 99,...], 16=>'a6', 26=>'b6', 36=>[54 | 99,...], <<_:16>> | [48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57,...] | {[[48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57,...],...]}=>[48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57 | 100 | 101,...]}=>atom() | [1..255,...]}
+map_galore.erl:1109: Function t_guard_bifs/1 has no local return
+map_galore.erl:1114: The pattern 'true' can never match the type 'false'
+map_galore.erl:1123: The pattern ~{}~ can never match the type #{'a':=1, <<_:16>>=>[104 | 105,...]}
+map_galore.erl:1140: The call map_galore:map_guard_sequence_1(#{'seq':=6, 'val':=[101,...]}) will never return since it differs in the 1st argument from the success typing arguments: (#{'seq':=1 | 2 | 3 | 4 | 5, 'val':=[97 | 98 | 99 | 100 | 101,...], #{'map':='key', 'one':='small'}=>[32 | 49 | 97 | 101 | 107 | 108 | 109 | 112 | 115 | 121,...], #{'map':='key', 'second':='small'}=>[32 | 50 | 97 | 101 | 107 | 108 | 109 | 112 | 115 | 121,...], #{'map':='key', 'third':='small'}=>[32 | 51 | 97 | 101 | 107 | 108 | 109 | 112 | 115 | 121,...], 10=>'a0', 11=>'a1', 12=>'a2', 13=>'a3', 14=>'a4', 15=>'a5', 16=>'a6', 17=>'a7', 18=>'a8', 19=>'a9', 20=>'b0', 21=>'b1', 22=>'b2', 23=>'b3', 24=>'b4', 25=>'b5', 26=>'b6', 27=>'b7', 28=>'b8', 29=>'b9', 30=>[48 | 99,...], 31=>[49 | 99,...], 32=>[50 | 99,...], 33=>[51 | 99,...], 34=>[52 | 99,...], 35=>[53 | 99,...], 36=>[54 | 99,...], 37=>[55 | 99,...], 38=>[56 | 99,...], 39=>[57 | 99,...], <<_:16>> | [48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57,...] | float() | {[any(),...]} | #{10:='a0', 11:='a1', 12:='a2', 13:='a3', 14:='a4', 15:='a5', 17:='a7', 18:='a8', 19:='a9', 20:='b0', 21:='b1', 22:='b2', 23:='b3', 24:='b4', 25:='b5', 27:='b7', 28:='b8', 29:='b9', 30:=[any(),...], 31:=[any(),...], 32:=[any(),...], 33:=[any(),...], 34:=[any(),...], 35:=[any(),...], 37:=[any(),...], 38:=[any(),...], 39:=[any(),...], 'k16'=>'a6', 'k26'=>'b6', 'k36'=>[any(),...], 16=>'a6', 26=>'b6', 36=>[any(),...], <<_:16>> | [any(),...] | {_}=>[any(),...]}=>atom() | [1..255,...]})
+map_galore.erl:1141: The call map_galore:map_guard_sequence_2(#{'b':=5}) will never return since it differs in the 1st argument from the success typing arguments: (#{'a':='gg' | 'kk' | 'sc' | 3 | 4, 'b'=>'other' | 3 | 4 | 5, 'c'=>'sc2', #{'map':='key', 'one':='small'}=>[32 | 49 | 97 | 101 | 107 | 108 | 109 | 112 | 115 | 121,...], #{'map':='key', 'second':='small'}=>[32 | 50 | 97 | 101 | 107 | 108 | 109 | 112 | 115 | 121,...], #{'map':='key', 'third':='small'}=>[32 | 51 | 97 | 101 | 107 | 108 | 109 | 112 | 115 | 121,...], 10=>'a0', 11=>'a1', 12=>'a2', 13=>'a3', 14=>'a4', 15=>'a5', 16=>'a6', 17=>'a7', 18=>'a8', 19=>'a9', 20=>'b0', 21=>'b1', 22=>'b2', 23=>'b3', 24=>'b4', 25=>'b5', 26=>'b6', 27=>'b7', 28=>'b8', 29=>'b9', 30=>[48 | 99,...], 31=>[49 | 99,...], 32=>[50 | 99,...], 33=>[51 | 99,...], 34=>[52 | 99,...], 35=>[53 | 99,...], 36=>[54 | 99,...], 37=>[55 | 99,...], 38=>[56 | 99,...], 39=>[57 | 99,...], <<_:16>> | [48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57,...] | float() | {[any(),...]} | #{10:='a0', 11:='a1', 12:='a2', 13:='a3', 14:='a4', 15:='a5', 17:='a7', 18:='a8', 19:='a9', 20:='b0', 21:='b1', 22:='b2', 23:='b3', 24:='b4', 25:='b5', 27:='b7', 28:='b8', 29:='b9', 30:=[any(),...], 31:=[any(),...], 32:=[any(),...], 33:=[any(),...], 34:=[any(),...], 35:=[any(),...], 37:=[any(),...], 38:=[any(),...], 39:=[any(),...], 'k16'=>'a6', 'k26'=>'b6', 'k36'=>[any(),...], 16=>'a6', 26=>'b6', 36=>[any(),...], <<_:16>> | [any(),...] | {_}=>[any(),...]}=>atom() | [1..255,...]})
+map_galore.erl:1209: The call map_galore:map_guard_sequence_1(#{'seq':=6, 'val':=[101,...], #{'map':='key', 'one':='small'}:=[32 | 49 | 97 | 101 | 107 | 108 | 109 | 112 | 115 | 121,...], #{'map':='key', 'second':='small'}:=[32 | 50 | 97 | 101 | 107 | 108 | 109 | 112 | 115 | 121,...], #{'map':='key', 'third':='small'}:=[32 | 51 | 97 | 101 | 107 | 108 | 109 | 112 | 115 | 121,...], 10:='a0', 11:='a1', 12:='a2', 13:='a3', 14:='a4', 15:='a5', 16:='a6', 17:='a7', 18:='a8', 19:='a9', 20:='b0', 21:='b1', 22:='b2', 23:='b3', 24:='b4', 25:='b5', 26:='b6', 27:='b7', 28:='b8', 29:='b9', 30:=[48 | 99,...], 31:=[49 | 99,...], 32:=[50 | 99,...], 33:=[51 | 99,...], 34:=[52 | 99,...], 35:=[53 | 99,...], 36:=[54 | 99,...], 37:=[55 | 99,...], 38:=[56 | 99,...], 39:=[57 | 99,...], <<_:16>> | [48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57,...] | float() | {[[48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57,...] | 3,...]} | #{10:='a0', 11:='a1', 12:='a2', 13:='a3', 14:='a4', 15:='a5', 17:='a7', 18:='a8', 19:='a9', 20:='b0', 21:='b1', 22:='b2', 23:='b3', 24:='b4', 25:='b5', 27:='b7', 28:='b8', 29:='b9', 30:=[48 | 99,...], 31:=[49 | 99,...], 32:=[50 | 99,...], 33:=[51 | 99,...], 34:=[52 | 99,...], 35:=[53 | 99,...], 37:=[55 | 99,...], 38:=[56 | 99,...], 39:=[57 | 99,...], 'k16'=>'a6', 'k26'=>'b6', 'k36'=>[54 | 99,...], 16=>'a6', 26=>'b6', 36=>[54 | 99,...], <<_:16>> | [48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57,...] | {[[48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57,...],...]}=>[48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57 | 100 | 101,...]}=>atom() | [1..255,...]}) will never return since it differs in the 1st argument from the success typing arguments: (#{'seq':=1 | 2 | 3 | 4 | 5, 'val':=[97 | 98 | 99 | 100 | 101,...], #{'map':='key', 'one':='small'}=>[32 | 49 | 97 | 101 | 107 | 108 | 109 | 112 | 115 | 121,...], #{'map':='key', 'second':='small'}=>[32 | 50 | 97 | 101 | 107 | 108 | 109 | 112 | 115 | 121,...], #{'map':='key', 'third':='small'}=>[32 | 51 | 97 | 101 | 107 | 108 | 109 | 112 | 115 | 121,...], 10=>'a0', 11=>'a1', 12=>'a2', 13=>'a3', 14=>'a4', 15=>'a5', 16=>'a6', 17=>'a7', 18=>'a8', 19=>'a9', 20=>'b0', 21=>'b1', 22=>'b2', 23=>'b3', 24=>'b4', 25=>'b5', 26=>'b6', 27=>'b7', 28=>'b8', 29=>'b9', 30=>[48 | 99,...], 31=>[49 | 99,...], 32=>[50 | 99,...], 33=>[51 | 99,...], 34=>[52 | 99,...], 35=>[53 | 99,...], 36=>[54 | 99,...], 37=>[55 | 99,...], 38=>[56 | 99,...], 39=>[57 | 99,...], <<_:16>> | [48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57,...] | float() | {[any(),...]} | #{10:='a0', 11:='a1', 12:='a2', 13:='a3', 14:='a4', 15:='a5', 17:='a7', 18:='a8', 19:='a9', 20:='b0', 21:='b1', 22:='b2', 23:='b3', 24:='b4', 25:='b5', 27:='b7', 28:='b8', 29:='b9', 30:=[any(),...], 31:=[any(),...], 32:=[any(),...], 33:=[any(),...], 34:=[any(),...], 35:=[any(),...], 37:=[any(),...], 38:=[any(),...], 39:=[any(),...], 'k16'=>'a6', 'k26'=>'b6', 'k36'=>[any(),...], 16=>'a6', 26=>'b6', 36=>[any(),...], <<_:16>> | [any(),...] | {_}=>[any(),...]}=>atom() | [1..255,...]})
+map_galore.erl:1210: The call map_galore:map_guard_sequence_2(#{'b':=5, #{'map':='key', 'one':='small'}:=[32 | 49 | 97 | 101 | 107 | 108 | 109 | 112 | 115 | 121,...], #{'map':='key', 'second':='small'}:=[32 | 50 | 97 | 101 | 107 | 108 | 109 | 112 | 115 | 121,...], #{'map':='key', 'third':='small'}:=[32 | 51 | 97 | 101 | 107 | 108 | 109 | 112 | 115 | 121,...], 10:='a0', 11:='a1', 12:='a2', 13:='a3', 14:='a4', 15:='a5', 16:='a6', 17:='a7', 18:='a8', 19:='a9', 20:='b0', 21:='b1', 22:='b2', 23:='b3', 24:='b4', 25:='b5', 26:='b6', 27:='b7', 28:='b8', 29:='b9', 30:=[48 | 99,...], 31:=[49 | 99,...], 32:=[50 | 99,...], 33:=[51 | 99,...], 34:=[52 | 99,...], 35:=[53 | 99,...], 36:=[54 | 99,...], 37:=[55 | 99,...], 38:=[56 | 99,...], 39:=[57 | 99,...], <<_:16>> | [48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57,...] | float() | {[[48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57,...] | 3,...]} | #{10:='a0', 11:='a1', 12:='a2', 13:='a3', 14:='a4', 15:='a5', 17:='a7', 18:='a8', 19:='a9', 20:='b0', 21:='b1', 22:='b2', 23:='b3', 24:='b4', 25:='b5', 27:='b7', 28:='b8', 29:='b9', 30:=[48 | 99,...], 31:=[49 | 99,...], 32:=[50 | 99,...], 33:=[51 | 99,...], 34:=[52 | 99,...], 35:=[53 | 99,...], 37:=[55 | 99,...], 38:=[56 | 99,...], 39:=[57 | 99,...], 'k16'=>'a6', 'k26'=>'b6', 'k36'=>[54 | 99,...], 16=>'a6', 26=>'b6', 36=>[54 | 99,...], <<_:16>> | [48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57,...] | {[[48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57,...],...]}=>[48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57 | 100 | 101,...]}=>atom() | [1..255,...]}) will never return since it differs in the 1st argument from the success typing arguments: (#{'a':='gg' | 'kk' | 'sc' | 3 | 4, 'b'=>'other' | 3 | 4 | 5, 'c'=>'sc2', #{'map':='key', 'one':='small'}=>[32 | 49 | 97 | 101 | 107 | 108 | 109 | 112 | 115 | 121,...], #{'map':='key', 'second':='small'}=>[32 | 50 | 97 | 101 | 107 | 108 | 109 | 112 | 115 | 121,...], #{'map':='key', 'third':='small'}=>[32 | 51 | 97 | 101 | 107 | 108 | 109 | 112 | 115 | 121,...], 10=>'a0', 11=>'a1', 12=>'a2', 13=>'a3', 14=>'a4', 15=>'a5', 16=>'a6', 17=>'a7', 18=>'a8', 19=>'a9', 20=>'b0', 21=>'b1', 22=>'b2', 23=>'b3', 24=>'b4', 25=>'b5', 26=>'b6', 27=>'b7', 28=>'b8', 29=>'b9', 30=>[48 | 99,...], 31=>[49 | 99,...], 32=>[50 | 99,...], 33=>[51 | 99,...], 34=>[52 | 99,...], 35=>[53 | 99,...], 36=>[54 | 99,...], 37=>[55 | 99,...], 38=>[56 | 99,...], 39=>[57 | 99,...], <<_:16>> | [48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57,...] | float() | {[any(),...]} | #{10:='a0', 11:='a1', 12:='a2', 13:='a3', 14:='a4', 15:='a5', 17:='a7', 18:='a8', 19:='a9', 20:='b0', 21:='b1', 22:='b2', 23:='b3', 24:='b4', 25:='b5', 27:='b7', 28:='b8', 29:='b9', 30:=[any(),...], 31:=[any(),...], 32:=[any(),...], 33:=[any(),...], 34:=[any(),...], 35:=[any(),...], 37:=[any(),...], 38:=[any(),...], 39:=[any(),...], 'k16'=>'a6', 'k26'=>'b6', 'k36'=>[any(),...], 16=>'a6', 26=>'b6', 36=>[any(),...], <<_:16>> | [any(),...] | {_}=>[any(),...]}=>atom() | [1..255,...]})
+map_galore.erl:1418: Fun application with arguments (#{'s':='none', 'v':='none'}) will never return since it differs in the 1st argument from the success typing arguments: (#{'s':='l' | 't' | 'v', 'v':='none' | <<_:16>> | [<<_:16>>,...] | {<<_:16>>,<<_:16>>}})
+map_galore.erl:1491: The test #{} =:= #{'a':=1} can never evaluate to 'true'
+map_galore.erl:1492: The test #{'a':=1} =:= #{} can never evaluate to 'true'
+map_galore.erl:1495: The test #{'a':=1} =:= #{'a':=2} can never evaluate to 'true'
+map_galore.erl:1496: The test #{'a':=2} =:= #{'a':=1} can never evaluate to 'true'
+map_galore.erl:1497: The test #{'a':=2, 'b':=1} =:= #{'a':=1, 'b':=3} can never evaluate to 'true'
+map_galore.erl:1498: The test #{'a':=1, 'b':=1} =:= #{'a':=1, 'b':=3} can never evaluate to 'true'
+map_galore.erl:1762: The call maps:get({1, 1},#{{1,float()}=>[101 | 108 | 112 | 116 | 117,...]}) will never return since the success typing arguments are (any(),map())
+map_galore.erl:1763: The call maps:get('a',#{}) will never return since the success typing arguments are (any(),map())
+map_galore.erl:1765: The call maps:get('a',#{'b':=1, 'c':=2}) will never return since the success typing arguments are (any(),map())
+map_galore.erl:186: The pattern ~{'x':=2}~ can never match the type #{'x':=3}
+map_galore.erl:187: The pattern ~{'x':=3}~ can never match the type {'a','b','c'}
+map_galore.erl:188: The pattern ~{'x':=3}~ can never match the type #{'y':=3}
+map_galore.erl:189: The pattern ~{'x':=3}~ can never match the type #{'x':=[101 | 104 | 114 | 116,...]}
+map_galore.erl:2304: Cons will produce an improper list since its 2nd argument is {'b','a'}
+map_galore.erl:2304: The call maps:from_list(nonempty_improper_list({'a','b'},{'b','a'})) will never return since it differs in the 1st argument from the success typing arguments: ([{_,_}])
+map_galore.erl:2305: The call maps:from_list('a') will never return since it differs in the 1st argument from the success typing arguments: ([{_,_}])
+map_galore.erl:2306: The call maps:from_list(42) will never return since it differs in the 1st argument from the success typing arguments: ([{_,_}])
+map_galore.erl:2735: Function t_has_map_fields/1 has no local return
+map_galore.erl:2743: The call map_galore:has_map_fields_2(#{'b':=2, 'c':=1}) will never return since it differs in the 1st argument from the success typing arguments: (#{'a':=3, 'b':=2, 'c':=1, 'x'=>42})
+map_galore.erl:2743: The pattern 'false' can never match the type 'true'
+map_galore.erl:2763: The pattern ~{}~ can never match the type #{'b':=2, 'c':=1, 'x'=>42}
+map_galore.erl:2765: Function has_map_fields_3/1 will never be called
+map_galore.erl:997: A key of type 'nonexisting' cannot exist in a map of type #{}
+map_galore.erl:998: A key of type 'nonexisting' cannot exist in a map of type #{1:='a', 2:='b', 4:='d', 5:='e', float()=>'c'}
diff --git a/lib/dialyzer/test/map_SUITE_data/results/map_in_guard2 b/lib/dialyzer/test/map_SUITE_data/results/map_in_guard2
index e3202badbe..6bc0c010d7 100644
--- a/lib/dialyzer/test/map_SUITE_data/results/map_in_guard2
+++ b/lib/dialyzer/test/map_SUITE_data/results/map_in_guard2
@@ -1,10 +1,13 @@
 
 map_in_guard2.erl:10: The call map_in_guard2:assoc_guard_clause('not_a_map') will never return since it differs in the 1st argument from the success typing arguments: (map())
 map_in_guard2.erl:12: The pattern 'true' can never match the type 'false'
+map_in_guard2.erl:14: The call map_in_guard2:exact_guard_clause(#{}) will never return since it differs in the 1st argument from the success typing arguments: (#{'a':=_, ...})
 map_in_guard2.erl:17: Clause guard cannot succeed. The variable M was matched against the type 'not_a_map'
 map_in_guard2.erl:20: Function assoc_update/1 has no local return
 map_in_guard2.erl:20: Guard test is_map(M::'not_a_map') can never succeed
 map_in_guard2.erl:22: Clause guard cannot succeed. The variable M was matched against the type 'not_a_map'
 map_in_guard2.erl:22: Function assoc_guard_clause/1 has no local return
+map_in_guard2.erl:24: Clause guard cannot succeed. The variable M was matched against the type #{}
+map_in_guard2.erl:27: Clause guard cannot succeed. The variable M was matched against the type #{}
 map_in_guard2.erl:27: Function exact_guard_clause/1 has no local return
 map_in_guard2.erl:8: The call map_in_guard2:assoc_update('not_a_map') will never return since it differs in the 1st argument from the success typing arguments: (map())
diff --git a/lib/dialyzer/test/map_SUITE_data/results/maps_merge b/lib/dialyzer/test/map_SUITE_data/results/maps_merge
new file mode 100644
index 0000000000..696f6e19d2
--- /dev/null
+++ b/lib/dialyzer/test/map_SUITE_data/results/maps_merge
@@ -0,0 +1,11 @@
+
+maps_merge.erl:10: The pattern #{_:=_} can never match the type #{'a':=1, 3:='ok', 'q'=>none(), 7=>none(), atom() | integer()=>_}
+maps_merge.erl:12: Function t3/0 has no local return
+maps_merge.erl:14: The pattern ~{7:='q'}~ can never match the type #{'a':=1, 3:='ok', 'q'=>none(), 7=>none(), atom() | integer()=>_}
+maps_merge.erl:16: Function t4/0 has no local return
+maps_merge.erl:18: The pattern ~{7:='q'}~ can never match the type #{'a':=1, 3:='ok', 'q'=>none(), 7=>none(), atom() | integer()=>_}
+maps_merge.erl:20: Function t5/0 has no local return
+maps_merge.erl:21: The pattern ~{'a':=2}~ can never match the type #{'a':=1, 'q'=>none(), 11=>_, atom()=>_}
+maps_merge.erl:5: Function t1/0 has no local return
+maps_merge.erl:6: The pattern ~{'a':=1}~ can never match the type #{}
+maps_merge.erl:8: Function t2/0 has no local return
diff --git a/lib/dialyzer/test/map_SUITE_data/results/typeflow b/lib/dialyzer/test/map_SUITE_data/results/typeflow
index 12f5f1459d..c4339e91a0 100644
--- a/lib/dialyzer/test/map_SUITE_data/results/typeflow
+++ b/lib/dialyzer/test/map_SUITE_data/results/typeflow
@@ -1,6 +1,9 @@
 
 typeflow.erl:12: Function a_is_integer/1 has no local return
+typeflow.erl:12: The pattern ~{'a':=X}~ can never match the type #{}
 typeflow.erl:14: Function t2/1 has no local return
+typeflow.erl:15: The call typeflow:a_is_integer(M::#{}) will never return since it differs in the 1st argument from the success typing arguments: (#{'a':=integer(), ...})
 typeflow.erl:19: Function t3/1 has no local return
 typeflow.erl:20: The call maps:get('a',M::#{}) will never return since the success typing arguments are (any(),map())
 typeflow.erl:5: Function t1/1 has no local return
+typeflow.erl:6: The call typeflow:a_is_integer(M::#{}) will never return since it differs in the 1st argument from the success typing arguments: (#{'a':=integer(), ...})
diff --git a/lib/dialyzer/test/map_SUITE_data/results/typeflow2 b/lib/dialyzer/test/map_SUITE_data/results/typeflow2
index b93a8599b7..aa47845fb1 100644
--- a/lib/dialyzer/test/map_SUITE_data/results/typeflow2
+++ b/lib/dialyzer/test/map_SUITE_data/results/typeflow2
@@ -1,6 +1,15 @@
 
+typeflow2.erl:10: The pattern ~{'a':=X}~ can never match the type #{'a'=>none(), _=>maybe_improper_list() | integer()}
+typeflow2.erl:11: The pattern ~{'a':=X}~ can never match the type #{'a'=>none(), _=>maybe_improper_list() | integer()}
 typeflow2.erl:26: Function t2/1 has no local return
 typeflow2.erl:29: The call lists:sort(integer()) will never return since it differs in the 1st argument from the success typing arguments: ([any()])
 typeflow2.erl:42: The pattern ~{'a':=X}~ can never match since previous clauses completely covered the type #{'a':=integer()}
 typeflow2.erl:43: The variable _ can never match since previous clauses completely covered the type #{'a':=integer()}
 typeflow2.erl:48: The pattern ~{}~ can never match the type #{'a':=atom() | maybe_improper_list() | integer()}
+typeflow2.erl:58: The pattern ~{'a':=X}~ can never match the type #{'a'=>none(), _=>maybe_improper_list() | integer()}
+typeflow2.erl:59: The pattern ~{'a':=X}~ can never match the type #{'a'=>none(), _=>maybe_improper_list() | integer()}
+typeflow2.erl:60: The pattern ~{'a':=X}~ can never match the type #{'a'=>none(), _=>maybe_improper_list() | integer()}
+typeflow2.erl:80: The pattern ~{'a':=X}~ can never match the type #{}
+typeflow2.erl:81: The pattern ~{'a':=X}~ can never match the type #{}
+typeflow2.erl:82: The pattern ~{'a':=X}~ can never match the type #{}
+typeflow2.erl:83: The pattern ~{'a':=X}~ can never match the type #{}
diff --git a/lib/dialyzer/test/map_SUITE_data/results/typesig b/lib/dialyzer/test/map_SUITE_data/results/typesig
index f5c7dacdbc..3049402860 100644
--- a/lib/dialyzer/test/map_SUITE_data/results/typesig
+++ b/lib/dialyzer/test/map_SUITE_data/results/typesig
@@ -2,4 +2,4 @@
 typesig.erl:5: Function t1/0 has no local return
 typesig.erl:5: The call typesig:test(#{'a':=1}) will never return since it differs in the 1st argument from the success typing arguments: (#{'a':={number()}, ...})
 typesig.erl:6: Function t2/0 has no local return
-typesig.erl:6: The call typesig:test(#{'a':={'b'}, ...}) will never return since it differs in the 1st argument from the success typing arguments: (#{'a':={number()}, ...})
+typesig.erl:6: The call typesig:test(#{'a':={'b'}}) will never return since it differs in the 1st argument from the success typing arguments: (#{'a':={number()}, ...})
diff --git a/lib/dialyzer/test/map_SUITE_data/src/exact.erl b/lib/dialyzer/test/map_SUITE_data/src/exact.erl
new file mode 100644
index 0000000000..e5ad02ec54
--- /dev/null
+++ b/lib/dialyzer/test/map_SUITE_data/src/exact.erl
@@ -0,0 +1,23 @@
+-module(exact).
+
+-export([t1/1, t2/1]).
+
+t1(M = #{}) ->
+    any_map(M),
+    case M of
+	#{a := _} -> error(fail);
+	_ -> ok
+    end.
+
+any_map(X) ->
+    X#{a => 1, a := 2}.
+
+t2(M = #{}) ->
+    has_a(M),
+    case M of
+	#{a := _} -> error(ok);
+	_ -> unreachable
+    end.
+
+has_a(M) ->
+    M#{a := 1, a => 2}.
diff --git a/lib/dialyzer/test/map_SUITE_data/src/guard_update.erl b/lib/dialyzer/test/map_SUITE_data/src/guard_update.erl
new file mode 100644
index 0000000000..19d0089401
--- /dev/null
+++ b/lib/dialyzer/test/map_SUITE_data/src/guard_update.erl
@@ -0,0 +1,18 @@
+-module(guard_update).
+
+-export([t/0, t2/0]).
+
+t() ->
+    f(#{a=>2}). %% Illegal
+
+f(M)
+  when M#{b := 7} =/= q
+       -> ok.
+
+t2() ->
+    f2(#{a=>2}). %% Legal!
+
+f2(M)
+  when M#{b := 7} =/= q;
+       M =/= p
+       -> ok.
diff --git a/lib/dialyzer/test/map_SUITE_data/src/initial_dataflow.erl b/lib/dialyzer/test/map_SUITE_data/src/initial_dataflow.erl
new file mode 100644
index 0000000000..bbc0d5682a
--- /dev/null
+++ b/lib/dialyzer/test/map_SUITE_data/src/initial_dataflow.erl
@@ -0,0 +1,11 @@
+-module(initial_dataflow).
+
+-export([test/0]).
+
+test() ->
+    false = assoc_guard(#{}),
+    true  = assoc_guard(not_a_map),
+    ok.
+
+assoc_guard(#{}) -> true;
+assoc_guard(Q) -> false.
diff --git a/lib/dialyzer/test/map_SUITE_data/src/map_galore.erl b/lib/dialyzer/test/map_SUITE_data/src/map_galore.erl
new file mode 100644
index 0000000000..2611241379
--- /dev/null
+++ b/lib/dialyzer/test/map_SUITE_data/src/map_galore.erl
@@ -0,0 +1,2824 @@
+%% %CopyrightBegin%
+%% 
+%% Copyright Ericsson AB 2013. All Rights Reserved.
+%% 
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%%     http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%% 
+%% %CopyrightEnd%
+%%
+-module(map_galore).
+-export([all/0, suite/0,groups/0,init_per_suite/1, end_per_suite/1, 
+	init_per_group/2,end_per_group/2
+    ]).
+
+-export([
+	t_build_and_match_literals/1, t_build_and_match_literals_large/1,
+	t_update_literals/1, t_update_literals_large/1,
+        t_match_and_update_literals/1, t_match_and_update_literals_large/1,
+	t_update_map_expressions/1,
+	t_update_assoc/1, t_update_assoc_large/1,
+        t_update_exact/1, t_update_exact_large/1,
+	t_guard_bifs/1,
+        t_guard_sequence/1, t_guard_sequence_large/1,
+        t_guard_update/1, t_guard_update_large/1,
+	t_guard_receive/1, t_guard_receive_large/1,
+        t_guard_fun/1,
+        t_update_deep/1,
+	t_list_comprehension/1,
+	t_map_sort_literals/1,
+	t_map_equal/1,
+	t_map_compare/1,
+	t_map_size/1,
+	t_is_map/1,
+
+	%% Specific Map BIFs
+	t_bif_map_get/1,
+	t_bif_map_find/1,
+	t_bif_map_is_key/1,
+	t_bif_map_keys/1,
+	t_bif_map_merge/1,
+	t_bif_map_new/1,
+	t_bif_map_put/1,
+	t_bif_map_remove/1,
+	t_bif_map_update/1,
+	t_bif_map_values/1,
+	t_bif_map_to_list/1,
+	t_bif_map_from_list/1,
+
+	%% erlang
+	t_erlang_hash/1,
+	t_map_encode_decode/1,
+
+	%% non specific BIF related
+	t_bif_build_and_check/1,
+	t_bif_merge_and_check/1,
+
+	%% maps module not bifs
+	t_maps_fold/1,
+	t_maps_map/1,
+	t_maps_size/1,
+	t_maps_without/1,
+
+	%% misc
+	t_erts_internal_order/1,
+        t_erts_internal_hash/1,
+	t_pdict/1,
+	t_ets/1,
+	t_dets/1,
+	t_tracing/1,
+
+	%% instruction-level tests
+	t_has_map_fields/1,
+	y_regs/1
+    ]).
+
+-include_lib("stdlib/include/ms_transform.hrl").
+
+-define(CHECK(Cond,Term),
+	case (catch (Cond)) of
+	    true -> true;
+	    _ -> io:format("###### CHECK FAILED ######~nINPUT:  ~p~n", [Term]),
+		 exit(Term)
+	end).
+
+suite() -> [].
+
+all() -> [
+	t_build_and_match_literals, t_build_and_match_literals_large,
+	t_update_literals, t_update_literals_large,
+        t_match_and_update_literals, t_match_and_update_literals_large,
+	t_update_map_expressions,
+	t_update_assoc, t_update_assoc_large,
+        t_update_exact, t_update_exact_large,
+	t_guard_bifs,
+        t_guard_sequence, t_guard_sequence_large,
+        t_guard_update, t_guard_update_large,
+	t_guard_receive, t_guard_receive_large,
+        t_guard_fun, t_list_comprehension,
+        t_update_deep,
+	t_map_equal, t_map_compare,
+	t_map_sort_literals,
+
+	%% Specific Map BIFs
+	t_bif_map_get,t_bif_map_find,t_bif_map_is_key,
+	t_bif_map_keys, t_bif_map_merge, t_bif_map_new,
+	t_bif_map_put,
+	t_bif_map_remove, t_bif_map_update,
+	t_bif_map_values,
+	t_bif_map_to_list, t_bif_map_from_list,
+
+	%% erlang
+	t_erlang_hash, t_map_encode_decode,
+	t_map_size, t_is_map,
+
+	%% non specific BIF related
+	t_bif_build_and_check,
+	t_bif_merge_and_check,
+
+	%% maps module
+	t_maps_fold, t_maps_map,
+	t_maps_size, t_maps_without,
+
+
+        %% Other functions
+	t_erts_internal_order,
+        t_erts_internal_hash,
+	t_pdict,
+	t_ets,
+	t_tracing,
+
+	%% instruction-level tests
+	t_has_map_fields,
+	y_regs
+    ].
+
+groups() -> [].
+
+init_per_suite(Config) -> Config.
+end_per_suite(_Config) -> ok.
+
+init_per_group(_GroupName, Config) -> Config.
+end_per_group(_GroupName, Config) -> Config.
+
+%% tests
+
+t_build_and_match_literals(Config) when is_list(Config) ->
+    #{} = #{},
+    #{1:=a} = #{1=>a},
+    #{1:=a,2:=b} = #{1=>a,2=>b},
+    #{1:=a,2:=b,3:="c"} = #{1=>a,2=>b,3=>"c"},
+    #{1:=a,2:=b,3:="c","4":="d"} = #{1=>a,2=>b,3=>"c","4"=>"d"},
+    #{1:=a,2:=b,3:="c","4":="d",<<"5">>:=<<"e">>} =
+	#{1=>a,2=>b,3=>"c","4"=>"d",<<"5">>=><<"e">>},
+    #{1:=a,2:=b,3:="c","4":="d",<<"5">>:=<<"e">>,{"6",7}:="f"} =
+	#{1=>a,2=>b,3=>"c","4"=>"d",<<"5">>=><<"e">>,{"6",7}=>"f"},
+    #{1:=a,2:=b,3:="c","4":="d",<<"5">>:=<<"e">>,{"6",7}:="f",8:=g} =
+	#{1=>a,2=>b,3=>"c","4"=>"d",<<"5">>=><<"e">>,{"6",7}=>"f",8=>g},
+
+    #{[]:=a,42.0:=b,x:={x,y},[a,b]:=list} =
+         #{[]=>a,42.0=>b,x=>{x,y},[a,b]=>list},
+
+    #{<<"hi all">> := 1} = #{<<"hi",32,"all">> => 1},
+
+    #{a:=X,a:=X=3,b:=4} = #{a=>3,b=>4}, % weird but ok =)
+
+    #{ a:=#{ b:=#{c := third, b:=second}}, b:=first} =
+	#{ b=>first, a=>#{ b=>#{c => third, b=> second}}},
+
+    M = #{ map_1=>#{ map_2=>#{value_3 => third}, value_2=> second}, value_1=>first},
+    M = #{ map_1:=#{ map_2:=#{value_3 := third}, value_2:= second}, value_1:=first} =
+	 #{ map_1=>#{ map_2=>#{value_3 => third}, value_2=> second}, value_1=>first},
+
+    %% error case
+    %V = 32,
+    %{'EXIT',{{badmatch,_},_}} = (catch (#{<<"hi all">> => 1} = #{<<"hi",V,"all">> => 1})),
+    {'EXIT',{{badmatch,_},_}} = (catch (#{x:=3,x:=2} = #{x=>3})),
+    {'EXIT',{{badmatch,_},_}} = (catch (#{x:=2} = #{x=>3})),
+    {'EXIT',{{badmatch,_},_}} = (catch (#{x:=3} = {a,b,c})),
+    {'EXIT',{{badmatch,_},_}} = (catch (#{x:=3} = #{y=>3})),
+    {'EXIT',{{badmatch,_},_}} = (catch (#{x:=3} = #{x=>"three"})),
+    ok.
+
+t_build_and_match_literals_large(Config) when is_list(Config) ->
+    % normal non-repeating
+    M0 = #{ 10=>a0,20=>b0,30=>"c0","40"=>"d0",<<"50">>=>"e0",{["00"]}=>"10",
+               11=>a1,21=>b1,31=>"c1","41"=>"d1",<<"51">>=>"e1",{["01"]}=>"11",
+               12=>a2,22=>b2,32=>"c2","42"=>"d2",<<"52">>=>"e2",{["02"]}=>"12",
+               13=>a3,23=>b3,33=>"c3","43"=>"d3",<<"53">>=>"e3",{["03"]}=>"13",
+               14=>a4,24=>b4,34=>"c4","44"=>"d4",<<"54">>=>"e4",{["04"]}=>"14",
+
+               15=>a5,25=>b5,35=>"c5","45"=>"d5",<<"55">>=>"e5",{["05"]}=>"15",
+               16=>a6,26=>b6,36=>"c6","46"=>"d6",<<"56">>=>"e6",{["06"]}=>"16",
+               17=>a7,27=>b7,37=>"c7","47"=>"d7",<<"57">>=>"e7",{["07"]}=>"17",
+               18=>a8,28=>b8,38=>"c8","48"=>"d8",<<"58">>=>"e8",{["08"]}=>"18",
+               19=>a9,29=>b9,39=>"c9","49"=>"d9",<<"59">>=>"e9",{["09"]}=>"19" },
+
+    #{10:=a0,20:=b0,30:="c0","40":="d0",<<"50">>:="e0",{["00"]}:="10"} = M0,
+    #{11:=a1,21:=b1,31:="c1","41":="d1",<<"51">>:="e1",{["01"]}:="11"} = M0,
+    #{12:=a2,22:=b2,32:="c2","42":="d2",<<"52">>:="e2",{["02"]}:="12"} = M0,
+    #{13:=a3,23:=b3,33:="c3","43":="d3",<<"53">>:="e3",{["03"]}:="13"} = M0,
+    #{14:=a4,24:=b4,34:="c4","44":="d4",<<"54">>:="e4",{["04"]}:="14"} = M0,
+
+    #{15:=a5,25:=b5,35:="c5","45":="d5",<<"55">>:="e5",{["05"]}:="15"} = M0,
+    #{16:=a6,26:=b6,36:="c6","46":="d6",<<"56">>:="e6",{["06"]}:="16"} = M0,
+    #{17:=a7,27:=b7,37:="c7","47":="d7",<<"57">>:="e7",{["07"]}:="17"} = M0,
+    #{18:=a8,28:=b8,38:="c8","48":="d8",<<"58">>:="e8",{["08"]}:="18"} = M0,
+    #{19:=a9,29:=b9,39:="c9","49":="d9",<<"59">>:="e9",{["09"]}:="19"} = M0,
+
+    60 = map_size(M0),
+    60 = maps:size(M0),
+
+    % with repeating
+    M1 = #{ 10=>a0,20=>b0,30=>"c0","40"=>"d0",<<"50">>=>"e0",{["00"]}=>"10",
+               11=>a1,21=>b1,31=>"c1","41"=>"d1",<<"51">>=>"e1",{["01"]}=>"11",
+               12=>a2,22=>b2,32=>"c2","42"=>"d2",<<"52">>=>"e2",{["02"]}=>"12",
+               13=>a3,23=>b3,33=>"c3","43"=>"d3",<<"53">>=>"e3",{["03"]}=>"13",
+               14=>a4,24=>b4,34=>"c4","44"=>"d4",<<"54">>=>"e4",{["04"]}=>"14",
+
+               10=>na0,20=>nb0,30=>"nc0","40"=>"nd0",<<"50">>=>"ne0",{["00"]}=>"n10",
+               11=>na1,21=>nb1,31=>"nc1","41"=>"nd1",<<"51">>=>"ne1",{["01"]}=>"n11",
+               12=>na2,22=>nb2,32=>"nc2","42"=>"nd2",<<"52">>=>"ne2",{["02"]}=>"n12",
+
+               15=>a5,25=>b5,35=>"c5","45"=>"d5",<<"55">>=>"e5",{["05"]}=>"15",
+               16=>a6,26=>b6,36=>"c6","46"=>"d6",<<"56">>=>"e6",{["06"]}=>"16",
+               17=>a7,27=>b7,37=>"c7","47"=>"d7",<<"57">>=>"e7",{["07"]}=>"17",
+
+               13=>na3,23=>nb3,33=>"nc3","43"=>"nd3",<<"53">>=>"ne3",{["03"]}=>"n13",
+               14=>na4,24=>nb4,34=>"nc4","44"=>"nd4",<<"54">>=>"ne4",{["04"]}=>"n14",
+
+               18=>a8,28=>b8,38=>"c8","48"=>"d8",<<"58">>=>"e8",{["08"]}=>"18",
+               19=>a9,29=>b9,39=>"c9","49"=>"d9",<<"59">>=>"e9",{["09"]}=>"19" },
+
+    #{10:=na0,20:=nb0,30:="nc0","40":="nd0",<<"50">>:="ne0",{["00"]}:="n10"} = M1,
+    #{11:=na1,21:=nb1,31:="nc1","41":="nd1",<<"51">>:="ne1",{["01"]}:="n11"} = M1,
+    #{12:=na2,22:=nb2,32:="nc2","42":="nd2",<<"52">>:="ne2",{["02"]}:="n12"} = M1,
+    #{13:=na3,23:=nb3,33:="nc3","43":="nd3",<<"53">>:="ne3",{["03"]}:="n13"} = M1,
+    #{14:=na4,24:=nb4,34:="nc4","44":="nd4",<<"54">>:="ne4",{["04"]}:="n14"} = M1,
+
+    #{15:=a5,25:=b5,35:="c5","45":="d5",<<"55">>:="e5",{["05"]}:="15"} = M1,
+    #{16:=a6,26:=b6,36:="c6","46":="d6",<<"56">>:="e6",{["06"]}:="16"} = M1,
+    #{17:=a7,27:=b7,37:="c7","47":="d7",<<"57">>:="e7",{["07"]}:="17"} = M1,
+    #{18:=a8,28:=b8,38:="c8","48":="d8",<<"58">>:="e8",{["08"]}:="18"} = M1,
+    #{19:=a9,29:=b9,39:="c9","49":="d9",<<"59">>:="e9",{["09"]}:="19"} = M1,
+
+    60 = map_size(M1),
+    60 = maps:size(M1),
+
+    % with floats
+
+    M2 = #{ 10=>a0,20=>b0,30=>"c0","40"=>"d0",<<"50">>=>"e0",{["00"]}=>"10",
+               11=>a1,21=>b1,31=>"c1","41"=>"d1",<<"51">>=>"e1",{["01"]}=>"11",
+               12=>a2,22=>b2,32=>"c2","42"=>"d2",<<"52">>=>"e2",{["02"]}=>"12",
+               13=>a3,23=>b3,33=>"c3","43"=>"d3",<<"53">>=>"e3",{["03"]}=>"13",
+               14=>a4,24=>b4,34=>"c4","44"=>"d4",<<"54">>=>"e4",{["04"]}=>"14",
+
+               15=>a5,25=>b5,35=>"c5","45"=>"d5",<<"55">>=>"e5",{["05"]}=>"15",
+               16=>a6,26=>b6,36=>"c6","46"=>"d6",<<"56">>=>"e6",{["06"]}=>"16",
+               17=>a7,27=>b7,37=>"c7","47"=>"d7",<<"57">>=>"e7",{["07"]}=>"17",
+               18=>a8,28=>b8,38=>"c8","48"=>"d8",<<"58">>=>"e8",{["08"]}=>"18",
+               19=>a9,29=>b9,39=>"c9","49"=>"d9",<<"59">>=>"e9",{["09"]}=>"19",
+
+               10.0=>fa0,20.0=>fb0,30.0=>"fc0",
+               11.0=>fa1,21.0=>fb1,31.0=>"fc1",
+               12.0=>fa2,22.0=>fb2,32.0=>"fc2",
+               13.0=>fa3,23.0=>fb3,33.0=>"fc3",
+               14.0=>fa4,24.0=>fb4,34.0=>"fc4",
+
+               15.0=>fa5,25.0=>fb5,35.0=>"fc5",
+               16.0=>fa6,26.0=>fb6,36.0=>"fc6",
+               17.0=>fa7,27.0=>fb7,37.0=>"fc7",
+               18.0=>fa8,28.0=>fb8,38.0=>"fc8",
+               19.0=>fa9,29.0=>fb9,39.0=>"fc9"},
+
+    #{10:=a0,20:=b0,30:="c0","40":="d0",<<"50">>:="e0",{["00"]}:="10"} = M2,
+    #{11:=a1,21:=b1,31:="c1","41":="d1",<<"51">>:="e1",{["01"]}:="11"} = M2,
+    #{12:=a2,22:=b2,32:="c2","42":="d2",<<"52">>:="e2",{["02"]}:="12"} = M2,
+    #{13:=a3,23:=b3,33:="c3","43":="d3",<<"53">>:="e3",{["03"]}:="13"} = M2,
+    #{14:=a4,24:=b4,34:="c4","44":="d4",<<"54">>:="e4",{["04"]}:="14"} = M2,
+
+    #{15:=a5,25:=b5,35:="c5","45":="d5",<<"55">>:="e5",{["05"]}:="15"} = M2,
+    #{16:=a6,26:=b6,36:="c6","46":="d6",<<"56">>:="e6",{["06"]}:="16"} = M2,
+    #{17:=a7,27:=b7,37:="c7","47":="d7",<<"57">>:="e7",{["07"]}:="17"} = M2,
+    #{18:=a8,28:=b8,38:="c8","48":="d8",<<"58">>:="e8",{["08"]}:="18"} = M2,
+    #{19:=a9,29:=b9,39:="c9","49":="d9",<<"59">>:="e9",{["09"]}:="19"} = M2,
+
+    #{10.0:=fa0,20.0:=fb0,30.0:="fc0","40":="d0",<<"50">>:="e0",{["00"]}:="10"} = M2,
+    #{11.0:=fa1,21.0:=fb1,31.0:="fc1","41":="d1",<<"51">>:="e1",{["01"]}:="11"} = M2,
+    #{12.0:=fa2,22.0:=fb2,32.0:="fc2","42":="d2",<<"52">>:="e2",{["02"]}:="12"} = M2,
+    #{13.0:=fa3,23.0:=fb3,33.0:="fc3","43":="d3",<<"53">>:="e3",{["03"]}:="13"} = M2,
+    #{14.0:=fa4,24.0:=fb4,34.0:="fc4","44":="d4",<<"54">>:="e4",{["04"]}:="14"} = M2,
+
+    #{15.0:=fa5,25.0:=fb5,35.0:="fc5","45":="d5",<<"55">>:="e5",{["05"]}:="15"} = M2,
+    #{16.0:=fa6,26.0:=fb6,36.0:="fc6","46":="d6",<<"56">>:="e6",{["06"]}:="16"} = M2,
+    #{17.0:=fa7,27.0:=fb7,37.0:="fc7","47":="d7",<<"57">>:="e7",{["07"]}:="17"} = M2,
+    #{18.0:=fa8,28.0:=fb8,38.0:="fc8","48":="d8",<<"58">>:="e8",{["08"]}:="18"} = M2,
+    #{19.0:=fa9,29.0:=fb9,39.0:="fc9","49":="d9",<<"59">>:="e9",{["09"]}:="19"} = M2,
+
+    90 = map_size(M2),
+    90 = maps:size(M2),
+
+    % with bignums
+    M3 = #{ 10=>a0,20=>b0,30=>"c0","40"=>"d0",<<"50">>=>"e0",{["00"]}=>"10",
+               11=>a1,21=>b1,31=>"c1","41"=>"d1",<<"51">>=>"e1",{["01"]}=>"11",
+               12=>a2,22=>b2,32=>"c2","42"=>"d2",<<"52">>=>"e2",{["02"]}=>"12",
+               13=>a3,23=>b3,33=>"c3","43"=>"d3",<<"53">>=>"e3",{["03"]}=>"13",
+               14=>a4,24=>b4,34=>"c4","44"=>"d4",<<"54">>=>"e4",{["04"]}=>"14",
+
+               15=>a5,25=>b5,35=>"c5","45"=>"d5",<<"55">>=>"e5",{["05"]}=>"15",
+               16=>a6,26=>b6,36=>"c6","46"=>"d6",<<"56">>=>"e6",{["06"]}=>"16",
+               17=>a7,27=>b7,37=>"c7","47"=>"d7",<<"57">>=>"e7",{["07"]}=>"17",
+               18=>a8,28=>b8,38=>"c8","48"=>"d8",<<"58">>=>"e8",{["08"]}=>"18",
+               19=>a9,29=>b9,39=>"c9","49"=>"d9",<<"59">>=>"e9",{["09"]}=>"19",
+
+               10.0=>fa0,20.0=>fb0,30.0=>"fc0",
+               11.0=>fa1,21.0=>fb1,31.0=>"fc1",
+               12.0=>fa2,22.0=>fb2,32.0=>"fc2",
+               13.0=>fa3,23.0=>fb3,33.0=>"fc3",
+               14.0=>fa4,24.0=>fb4,34.0=>"fc4",
+
+               15.0=>fa5,25.0=>fb5,35.0=>"fc5",
+               16.0=>fa6,26.0=>fb6,36.0=>"fc6",
+               17.0=>fa7,27.0=>fb7,37.0=>"fc7",
+               18.0=>fa8,28.0=>fb8,38.0=>"fc8",
+               19.0=>fa9,29.0=>fb9,39.0=>"fc9",
+
+               36893488147419103232=>big1,  73786976294838206464=>big2,
+               147573952589676412928=>big3, 18446744073709551616=>big4,
+               4294967296=>big5,            8589934592=>big6,
+               4294967295=>big7,            67108863=>big8
+             },
+
+    #{10:=a0,20:=b0,30:="c0","40":="d0",<<"50">>:="e0",{["00"]}:="10"} = M3,
+    #{11:=a1,21:=b1,31:="c1","41":="d1",<<"51">>:="e1",{["01"]}:="11"} = M3,
+    #{12:=a2,22:=b2,32:="c2","42":="d2",<<"52">>:="e2",{["02"]}:="12"} = M3,
+    #{13:=a3,23:=b3,33:="c3","43":="d3",<<"53">>:="e3",{["03"]}:="13"} = M3,
+    #{14:=a4,24:=b4,34:="c4","44":="d4",<<"54">>:="e4",{["04"]}:="14"} = M3,
+
+    #{15:=a5,25:=b5,35:="c5","45":="d5",<<"55">>:="e5",{["05"]}:="15"} = M3,
+    #{16:=a6,26:=b6,36:="c6","46":="d6",<<"56">>:="e6",{["06"]}:="16"} = M3,
+    #{17:=a7,27:=b7,37:="c7","47":="d7",<<"57">>:="e7",{["07"]}:="17"} = M3,
+    #{18:=a8,28:=b8,38:="c8","48":="d8",<<"58">>:="e8",{["08"]}:="18"} = M3,
+    #{19:=a9,29:=b9,39:="c9","49":="d9",<<"59">>:="e9",{["09"]}:="19"} = M3,
+
+    #{10.0:=fa0,20.0:=fb0,30.0:="fc0","40":="d0",<<"50">>:="e0",{["00"]}:="10"} = M3,
+    #{11.0:=fa1,21.0:=fb1,31.0:="fc1","41":="d1",<<"51">>:="e1",{["01"]}:="11"} = M3,
+    #{12.0:=fa2,22.0:=fb2,32.0:="fc2","42":="d2",<<"52">>:="e2",{["02"]}:="12"} = M3,
+    #{13.0:=fa3,23.0:=fb3,33.0:="fc3","43":="d3",<<"53">>:="e3",{["03"]}:="13"} = M3,
+    #{14.0:=fa4,24.0:=fb4,34.0:="fc4","44":="d4",<<"54">>:="e4",{["04"]}:="14"} = M3,
+
+    #{15.0:=fa5,25.0:=fb5,35.0:="fc5","45":="d5",<<"55">>:="e5",{["05"]}:="15"} = M3,
+    #{16.0:=fa6,26.0:=fb6,36.0:="fc6","46":="d6",<<"56">>:="e6",{["06"]}:="16"} = M3,
+    #{17.0:=fa7,27.0:=fb7,37.0:="fc7","47":="d7",<<"57">>:="e7",{["07"]}:="17"} = M3,
+    #{18.0:=fa8,28.0:=fb8,38.0:="fc8","48":="d8",<<"58">>:="e8",{["08"]}:="18"} = M3,
+    #{19.0:=fa9,29.0:=fb9,39.0:="fc9","49":="d9",<<"59">>:="e9",{["09"]}:="19"} = M3,
+
+    #{36893488147419103232:=big1,67108863:=big8,"45":="d5",<<"55">>:="e5",{["05"]}:="15"} = M3,
+    #{147573952589676412928:=big3,8589934592:=big6,"46":="d6",<<"56">>:="e6",{["06"]}:="16"} = M3,
+    #{4294967296:=big5,18446744073709551616:=big4,"47":="d7",<<"57">>:="e7",{["07"]}:="17"} = M3,
+    #{4294967295:=big7,73786976294838206464:=big2,"48":="d8",<<"58">>:="e8",{["08"]}:="18"} = M3,
+
+    98 = map_size(M3),
+    98 = maps:size(M3),
+
+    %% with maps
+
+    M4 = #{ 10=>a0,20=>b0,30=>"c0","40"=>"d0",<<"50">>=>"e0",{["00"]}=>"10",
+               11=>a1,21=>b1,31=>"c1","41"=>"d1",<<"51">>=>"e1",{["01"]}=>"11",
+               12=>a2,22=>b2,32=>"c2","42"=>"d2",<<"52">>=>"e2",{["02"]}=>"12",
+               13=>a3,23=>b3,33=>"c3","43"=>"d3",<<"53">>=>"e3",{["03"]}=>"13",
+               14=>a4,24=>b4,34=>"c4","44"=>"d4",<<"54">>=>"e4",{["04"]}=>"14",
+
+               15=>a5,25=>b5,35=>"c5","45"=>"d5",<<"55">>=>"e5",{["05"]}=>"15",
+               16=>a6,26=>b6,36=>"c6","46"=>"d6",<<"56">>=>"e6",{["06"]}=>"16",
+               17=>a7,27=>b7,37=>"c7","47"=>"d7",<<"57">>=>"e7",{["07"]}=>"17",
+               18=>a8,28=>b8,38=>"c8","48"=>"d8",<<"58">>=>"e8",{["08"]}=>"18",
+               19=>a9,29=>b9,39=>"c9","49"=>"d9",<<"59">>=>"e9",{["09"]}=>"19",
+
+               10.0=>fa0,20.0=>fb0,30.0=>"fc0",
+               11.0=>fa1,21.0=>fb1,31.0=>"fc1",
+               12.0=>fa2,22.0=>fb2,32.0=>"fc2",
+               13.0=>fa3,23.0=>fb3,33.0=>"fc3",
+               14.0=>fa4,24.0=>fb4,34.0=>"fc4",
+
+               15.0=>fa5,25.0=>fb5,35.0=>"fc5",
+               16.0=>fa6,26.0=>fb6,36.0=>"fc6",
+               17.0=>fa7,27.0=>fb7,37.0=>"fc7",
+               18.0=>fa8,28.0=>fb8,38.0=>"fc8",
+               19.0=>fa9,29.0=>fb9,39.0=>"fc9",
+
+               #{ one => small, map => key } => "small map key 1",
+               #{ second => small, map => key } => "small map key 2",
+               #{ third => small, map => key } => "small map key 3",
+
+               #{ 10=>a0,20=>b0,30=>"c0","40"=>"d0",<<"50">>=>"e0",{["00"]}=>"10",
+                  11=>a1,21=>b1,31=>"c1","41"=>"d1",<<"51">>=>"e1",{["01"]}=>"11",
+                  12=>a2,22=>b2,32=>"c2","42"=>"d2",<<"52">>=>"e2",{["02"]}=>"12",
+                  13=>a3,23=>b3,33=>"c3","43"=>"d3",<<"53">>=>"e3",{["03"]}=>"13",
+                  14=>a4,24=>b4,34=>"c4","44"=>"d4",<<"54">>=>"e4",{["04"]}=>"14",
+
+                  15=>a5,25=>b5,35=>"c5","45"=>"d5",<<"55">>=>"e5",{["05"]}=>"15",
+                  16=>a6,26=>b6,36=>"c6","46"=>"d6",<<"56">>=>"e6",{["06"]}=>"16",
+                  17=>a7,27=>b7,37=>"c7","47"=>"d7",<<"57">>=>"e7",{["07"]}=>"17",
+                  18=>a8,28=>b8,38=>"c8","48"=>"d8",<<"58">>=>"e8",{["08"]}=>"18",
+                  19=>a9,29=>b9,39=>"c9","49"=>"d9",<<"59">>=>"e9",{["09"]}=>"19" } => "large map key 1",
+
+               #{ 10=>a0,20=>b0,30=>"c0","40"=>"d0",<<"50">>=>"e0",{["00"]}=>"10",
+                  11=>a1,21=>b1,31=>"c1","41"=>"d1",<<"51">>=>"e1",{["01"]}=>"11",
+                  12=>a2,22=>b2,32=>"c2","42"=>"d2",<<"52">>=>"e2",{["02"]}=>"12",
+                  13=>a3,23=>b3,33=>"c3","43"=>"d3",<<"53">>=>"e3",{["03"]}=>"13",
+                  14=>a4,24=>b4,34=>"c4","44"=>"d4",<<"54">>=>"e4",{["04"]}=>"14",
+
+                  15=>a5,25=>b5,35=>"c5","45"=>"d5",<<"55">>=>"e5",{["05"]}=>"15",
+                  k16=>a6,k26=>b6,k36=>"c6","46"=>"d6",<<"56">>=>"e6",{["06"]}=>"16",
+                  17=>a7,27=>b7,37=>"c7","47"=>"d7",<<"57">>=>"e7",{["07"]}=>"17",
+                  18=>a8,28=>b8,38=>"c8","48"=>"d8",<<"58">>=>"e8",{["08"]}=>"18",
+                  19=>a9,29=>b9,39=>"c9","49"=>"d9",<<"59">>=>"e9",{["09"]}=>"19" } => "large map key 2" },
+
+    #{10:=a0,20:=b0,30:="c0","40":="d0",<<"50">>:="e0",{["00"]}:="10"} = M4,
+    #{11:=a1,21:=b1,31:="c1","41":="d1",<<"51">>:="e1",{["01"]}:="11"} = M4,
+    #{12:=a2,22:=b2,32:="c2","42":="d2",<<"52">>:="e2",{["02"]}:="12"} = M4,
+    #{13:=a3,23:=b3,33:="c3","43":="d3",<<"53">>:="e3",{["03"]}:="13"} = M4,
+    #{14:=a4,24:=b4,34:="c4","44":="d4",<<"54">>:="e4",{["04"]}:="14"} = M4,
+
+    #{15:=a5,25:=b5,35:="c5","45":="d5",<<"55">>:="e5",{["05"]}:="15"} = M4,
+    #{16:=a6,26:=b6,36:="c6","46":="d6",<<"56">>:="e6",{["06"]}:="16"} = M4,
+    #{17:=a7,27:=b7,37:="c7","47":="d7",<<"57">>:="e7",{["07"]}:="17"} = M4,
+    #{18:=a8,28:=b8,38:="c8","48":="d8",<<"58">>:="e8",{["08"]}:="18"} = M4,
+    #{19:=a9,29:=b9,39:="c9","49":="d9",<<"59">>:="e9",{["09"]}:="19"} = M4,
+
+    #{ #{ one => small, map => key }    := "small map key 1",
+       #{ second => small, map => key } := "small map key 2",
+       #{ third => small, map => key }  := "small map key 3" } = M4,
+
+    #{ #{ 10=>a0,20=>b0,30=>"c0","40"=>"d0",<<"50">>=>"e0",{["00"]}=>"10",
+          11=>a1,21=>b1,31=>"c1","41"=>"d1",<<"51">>=>"e1",{["01"]}=>"11",
+          12=>a2,22=>b2,32=>"c2","42"=>"d2",<<"52">>=>"e2",{["02"]}=>"12",
+          13=>a3,23=>b3,33=>"c3","43"=>"d3",<<"53">>=>"e3",{["03"]}=>"13",
+          14=>a4,24=>b4,34=>"c4","44"=>"d4",<<"54">>=>"e4",{["04"]}=>"14",
+
+          15=>a5,25=>b5,35=>"c5","45"=>"d5",<<"55">>=>"e5",{["05"]}=>"15",
+          16=>a6,26=>b6,36=>"c6","46"=>"d6",<<"56">>=>"e6",{["06"]}=>"16",
+          17=>a7,27=>b7,37=>"c7","47"=>"d7",<<"57">>=>"e7",{["07"]}=>"17",
+          18=>a8,28=>b8,38=>"c8","48"=>"d8",<<"58">>=>"e8",{["08"]}=>"18",
+          19=>a9,29=>b9,39=>"c9","49"=>"d9",<<"59">>=>"e9",{["09"]}=>"19" } := "large map key 1",
+
+       #{ 10=>a0,20=>b0,30=>"c0","40"=>"d0",<<"50">>=>"e0",{["00"]}=>"10",
+          11=>a1,21=>b1,31=>"c1","41"=>"d1",<<"51">>=>"e1",{["01"]}=>"11",
+          12=>a2,22=>b2,32=>"c2","42"=>"d2",<<"52">>=>"e2",{["02"]}=>"12",
+          13=>a3,23=>b3,33=>"c3","43"=>"d3",<<"53">>=>"e3",{["03"]}=>"13",
+          14=>a4,24=>b4,34=>"c4","44"=>"d4",<<"54">>=>"e4",{["04"]}=>"14",
+
+          15=>a5,25=>b5,35=>"c5","45"=>"d5",<<"55">>=>"e5",{["05"]}=>"15",
+          k16=>a6,k26=>b6,k36=>"c6","46"=>"d6",<<"56">>=>"e6",{["06"]}=>"16",
+          17=>a7,27=>b7,37=>"c7","47"=>"d7",<<"57">>=>"e7",{["07"]}=>"17",
+          18=>a8,28=>b8,38=>"c8","48"=>"d8",<<"58">>=>"e8",{["08"]}=>"18",
+          19=>a9,29=>b9,39=>"c9","49"=>"d9",<<"59">>=>"e9",{["09"]}=>"19" } := "large map key 2" } = M4,
+
+
+    #{ 15:=V1,25:=b5,35:=V2,"45":="d5",<<"55">>:=V3,{["05"]}:="15",
+       #{ one => small, map => key }    := "small map key 1",
+       #{ second => small, map => key } := V4,
+       #{ third => small, map => key }  := "small map key 3",
+       #{ 10=>a0,20=>b0,30=>"c0","40"=>"d0",<<"50">>=>"e0",{["00"]}=>"10",
+          11=>a1,21=>b1,31=>"c1","41"=>"d1",<<"51">>=>"e1",{["01"]}=>"11",
+          12=>a2,22=>b2,32=>"c2","42"=>"d2",<<"52">>=>"e2",{["02"]}=>"12",
+          13=>a3,23=>b3,33=>"c3","43"=>"d3",<<"53">>=>"e3",{["03"]}=>"13",
+          14=>a4,24=>b4,34=>"c4","44"=>"d4",<<"54">>=>"e4",{["04"]}=>"14",
+
+          15=>a5,25=>b5,35=>"c5","45"=>"d5",<<"55">>=>"e5",{["05"]}=>"15",
+          16=>a6,26=>b6,36=>"c6","46"=>"d6",<<"56">>=>"e6",{["06"]}=>"16",
+          17=>a7,27=>b7,37=>"c7","47"=>"d7",<<"57">>=>"e7",{["07"]}=>"17",
+          18=>a8,28=>b8,38=>"c8","48"=>"d8",<<"58">>=>"e8",{["08"]}=>"18",
+          19=>a9,29=>b9,39=>"c9","49"=>"d9",<<"59">>=>"e9",{["09"]}=>"19" } := V5 } = M4,
+
+    a5   = V1,
+    "c5" = V2,
+    "e5" = V3,
+    "small map key 2" = V4,
+    "large map key 1" = V5,
+
+    95 = map_size(M4),
+    95 = maps:size(M4),
+
+    % call for value
+
+    M5 = #{ 10=>a0,20=>b0,30=>"c0","40"=>"d0",<<"50">>=>"e0",{["00"]}=>"10",
+               11=>a1,21=>b1,31=>"c1","41"=>"d1",<<"51">>=>"e1",{["01"]}=>"11",
+               12=>a2,22=>b2,32=>"c2","42"=>"d2",<<"52">>=>"e2",{["02"]}=>"12",
+               13=>a3,23=>b3,33=>"c3","43"=>"d3",<<"53">>=>"e3",{["03"]}=>"13",
+               14=>a4,24=>b4,34=>"c4","44"=>"d4",<<"54">>=>"e4",{["04"]}=>"14",
+
+               15=>a5,25=>b5,35=>"c5","45"=>"d5",<<"55">>=>"e5",{["05"]}=>"15",
+               16=>a6,26=>b6,36=>"c6","46"=>"d6",<<"56">>=>"e6",{["06"]}=>"16",
+               17=>a7,27=>b7,37=>"c7","47"=>"d7",<<"57">>=>"e7",{["07"]}=>"17",
+               18=>a8,28=>b8,38=>"c8","48"=>"d8",<<"58">>=>"e8",{["08"]}=>"18",
+               19=>a9,29=>b9,39=>"c9","49"=>"d9",<<"59">>=>"e9",{["09"]}=>"19",
+
+               10.0=>fa0,20.0=>fb0,30.0=>"fc0",
+               11.0=>fa1,21.0=>fb1,31.0=>"fc1",
+               12.0=>fa2,22.0=>fb2,32.0=>"fc2",
+               13.0=>fa3,23.0=>fb3,33.0=>"fc3",
+               14.0=>fa4,24.0=>fb4,34.0=>"fc4",
+
+               15.0=>fa5,25.0=>fb5,35.0=>"fc5",
+               16.0=>fa6,26.0=>fb6,36.0=>"fc6",
+               17.0=>fa7,27.0=>fb7,37.0=>"fc7",
+               18.0=>fa8,28.0=>fb8,38.0=>"fc8",
+               19.0=>fa9,29.0=>fb9,39.0=>"fc9",
+
+               #{ one => small, map => key } => "small map key 1",
+               #{ second => small, map => key } => "small map key 2",
+               #{ third => small, map => key } => "small map key 3",
+
+               #{ 10=>a0,20=>b0,30=>"c0","40"=>"d0",<<"50">>=>"e0",{["00"]}=>"10",
+                  11=>a1,21=>b1,31=>"c1","41"=>"d1",<<"51">>=>"e1",{["01"]}=>"11",
+                  12=>a2,22=>b2,32=>"c2","42"=>"d2",<<"52">>=>"e2",{["02"]}=>"12",
+                  13=>a3,23=>b3,33=>"c3","43"=>"d3",<<"53">>=>"e3",{["03"]}=>"13",
+                  14=>a4,24=>b4,34=>"c4","44"=>"d4",<<"54">>=>"e4",{["04"]}=>"14",
+
+                  15=>a5,25=>b5,35=>"c5","45"=>"d5",<<"55">>=>"e5",{["05"]}=>"15",
+                  16=>a6,26=>b6,36=>"c6","46"=>"d6",<<"56">>=>"e6",{["06"]}=>"16",
+                  17=>a7,27=>b7,37=>"c7","47"=>"d7",<<"57">>=>"e7",{["07"]}=>"17",
+                  18=>a8,28=>b8,38=>"c8","48"=>"d8",<<"58">>=>"e8",{["08"]}=>"18",
+                  19=>a9,29=>b9,39=>"c9","49"=>"d9",<<"59">>=>"e9",{["09"]}=>"19" } => "large map key 1",
+
+               #{ 10=>a0,20=>b0,30=>"c0","40"=>"d0",<<"50">>=>"e0",{["00"]}=>"10",
+                  11=>a1,21=>b1,31=>"c1","41"=>"d1",<<"51">>=>"e1",{["01"]}=>"11",
+                  12=>a2,22=>b2,32=>"c2","42"=>"d2",<<"52">>=>"e2",{["02"]}=>"12",
+                  13=>a3,23=>b3,33=>"c3","43"=>"d3",<<"53">>=>"e3",{["03"]}=>"13",
+                  14=>a4,24=>b4,34=>"c4","44"=>"d4",<<"54">>=>"e4",{["04"]}=>"14",
+
+                  15=>a5,25=>b5,35=>"c5","45"=>"d5",<<"55">>=>"e5",{["05"]}=>"15",
+                  k16=>a6,k26=>b6,k36=>"c6","46"=>"d6",<<"56">>=>"e6",{["06"]}=>"16",
+                  17=>a7,27=>b7,37=>"c7","47"=>"d7",<<"57">>=>"e7",{["07"]}=>"17",
+                  18=>a8,28=>b8,38=>"c8","48"=>"d8",<<"58">>=>"e8",{["08"]}=>"18",
+                  19=>a9,29=>b9,39=>"c9","49"=>"d9",<<"59">>=>"e9",{["09"]}=>"19" } => "large map key 2" },
+
+    #{10:=a0,20:=b0,30:="c0","40":="d0",<<"50">>:="e0",{["00"]}:="10"} = M5,
+    #{11:=a1,21:=b1,31:="c1","41":="d1",<<"51">>:="e1",{["01"]}:="11"} = M5,
+    #{12:=a2,22:=b2,32:="c2","42":="d2",<<"52">>:="e2",{["02"]}:="12"} = M5,
+    #{13:=a3,23:=b3,33:="c3","43":="d3",<<"53">>:="e3",{["03"]}:="13"} = M5,
+    #{14:=a4,24:=b4,34:="c4","44":="d4",<<"54">>:="e4",{["04"]}:="14"} = M5,
+
+    #{15:=a5,25:=b5,35:="c5","45":="d5",<<"55">>:="e5",{["05"]}:="15"} = M5,
+    #{16:=a6,26:=b6,36:="c6","46":="d6",<<"56">>:="e6",{["06"]}:="16"} = M5,
+    #{17:=a7,27:=b7,37:="c7","47":="d7",<<"57">>:="e7",{["07"]}:="17"} = M5,
+    #{18:=a8,28:=b8,38:="c8","48":="d8",<<"58">>:="e8",{["08"]}:="18"} = M5,
+    #{19:=a9,29:=b9,39:="c9","49":="d9",<<"59">>:="e9",{["09"]}:="19"} = M5,
+
+    #{ #{ one => small, map => key }    := "small map key 1",
+       #{ second => small, map => key } := "small map key 2",
+       #{ third => small, map => key }  := "small map key 3" } = M5,
+
+    #{ #{ 10=>a0,20=>b0,30=>"c0","40"=>"d0",<<"50">>=>"e0",{["00"]}=>"10",
+          11=>a1,21=>b1,31=>"c1","41"=>"d1",<<"51">>=>"e1",{["01"]}=>"11",
+          12=>a2,22=>b2,32=>"c2","42"=>"d2",<<"52">>=>"e2",{["02"]}=>"12",
+          13=>a3,23=>b3,33=>"c3","43"=>"d3",<<"53">>=>"e3",{["03"]}=>"13",
+          14=>a4,24=>b4,34=>"c4","44"=>"d4",<<"54">>=>"e4",{["04"]}=>"14",
+
+          15=>a5,25=>b5,35=>"c5","45"=>"d5",<<"55">>=>"e5",{["05"]}=>"15",
+          16=>a6,26=>b6,36=>"c6","46"=>"d6",<<"56">>=>"e6",{["06"]}=>"16",
+          17=>a7,27=>b7,37=>"c7","47"=>"d7",<<"57">>=>"e7",{["07"]}=>"17",
+          18=>a8,28=>b8,38=>"c8","48"=>"d8",<<"58">>=>"e8",{["08"]}=>"18",
+          19=>a9,29=>b9,39=>"c9","49"=>"d9",<<"59">>=>"e9",{["09"]}=>"19" } := "large map key 1",
+
+       #{ 10=>a0,20=>b0,30=>"c0","40"=>"d0",<<"50">>=>"e0",{["00"]}=>"10",
+          11=>a1,21=>b1,31=>"c1","41"=>"d1",<<"51">>=>"e1",{["01"]}=>"11",
+          12=>a2,22=>b2,32=>"c2","42"=>"d2",<<"52">>=>"e2",{["02"]}=>"12",
+          13=>a3,23=>b3,33=>"c3","43"=>"d3",<<"53">>=>"e3",{["03"]}=>"13",
+          14=>a4,24=>b4,34=>"c4","44"=>"d4",<<"54">>=>"e4",{["04"]}=>"14",
+
+          15=>a5,25=>b5,35=>"c5","45"=>"d5",<<"55">>=>"e5",{["05"]}=>"15",
+          k16=>a6,k26=>b6,k36=>"c6","46"=>"d6",<<"56">>=>"e6",{["06"]}=>"16",
+          17=>a7,27=>b7,37=>"c7","47"=>"d7",<<"57">>=>"e7",{["07"]}=>"17",
+          18=>a8,28=>b8,38=>"c8","48"=>"d8",<<"58">>=>"e8",{["08"]}=>"18",
+          19=>a9,29=>b9,39=>"c9","49"=>"d9",<<"59">>=>"e9",{["09"]}=>"19" } := "large map key 2" } = M5,
+
+    95 = map_size(M5),
+    95 = maps:size(M5),
+
+    %% remember
+
+    #{10:=a0,20:=b0,30:="c0","40":="d0",<<"50">>:="e0",{["00"]}:="10"} = M0,
+    #{11:=a1,21:=b1,31:="c1","41":="d1",<<"51">>:="e1",{["01"]}:="11"} = M0,
+    #{12:=a2,22:=b2,32:="c2","42":="d2",<<"52">>:="e2",{["02"]}:="12"} = M0,
+    #{13:=a3,23:=b3,33:="c3","43":="d3",<<"53">>:="e3",{["03"]}:="13"} = M0,
+    #{14:=a4,24:=b4,34:="c4","44":="d4",<<"54">>:="e4",{["04"]}:="14"} = M0,
+
+    #{10:=na0,20:=nb0,30:="nc0","40":="nd0",<<"50">>:="ne0",{["00"]}:="n10"} = M1,
+    #{11:=na1,21:=nb1,31:="nc1","41":="nd1",<<"51">>:="ne1",{["01"]}:="n11"} = M1,
+    #{12:=na2,22:=nb2,32:="nc2","42":="nd2",<<"52">>:="ne2",{["02"]}:="n12"} = M1,
+    #{13:=na3,23:=nb3,33:="nc3","43":="nd3",<<"53">>:="ne3",{["03"]}:="n13"} = M1,
+    #{14:=na4,24:=nb4,34:="nc4","44":="nd4",<<"54">>:="ne4",{["04"]}:="n14"} = M1,
+
+    #{15:=a5,25:=b5,35:="c5","45":="d5",<<"55">>:="e5",{["05"]}:="15"} = M1,
+    #{16:=a6,26:=b6,36:="c6","46":="d6",<<"56">>:="e6",{["06"]}:="16"} = M1,
+    #{17:=a7,27:=b7,37:="c7","47":="d7",<<"57">>:="e7",{["07"]}:="17"} = M1,
+    #{18:=a8,28:=b8,38:="c8","48":="d8",<<"58">>:="e8",{["08"]}:="18"} = M1,
+    #{19:=a9,29:=b9,39:="c9","49":="d9",<<"59">>:="e9",{["09"]}:="19"} = M1,
+
+    #{15:=a5,25:=b5,35:="c5","45":="d5",<<"55">>:="e5",{["05"]}:="15"} = M2,
+    #{16:=a6,26:=b6,36:="c6","46":="d6",<<"56">>:="e6",{["06"]}:="16"} = M2,
+    #{17:=a7,27:=b7,37:="c7","47":="d7",<<"57">>:="e7",{["07"]}:="17"} = M2,
+    #{18:=a8,28:=b8,38:="c8","48":="d8",<<"58">>:="e8",{["08"]}:="18"} = M2,
+    #{19:=a9,29:=b9,39:="c9","49":="d9",<<"59">>:="e9",{["09"]}:="19"} = M2,
+
+    #{10.0:=fa0,20.0:=fb0,30.0:="fc0","40":="d0",<<"50">>:="e0",{["00"]}:="10"} = M2,
+    #{11.0:=fa1,21.0:=fb1,31.0:="fc1","41":="d1",<<"51">>:="e1",{["01"]}:="11"} = M2,
+    #{12.0:=fa2,22.0:=fb2,32.0:="fc2","42":="d2",<<"52">>:="e2",{["02"]}:="12"} = M2,
+    #{13.0:=fa3,23.0:=fb3,33.0:="fc3","43":="d3",<<"53">>:="e3",{["03"]}:="13"} = M2,
+    #{14.0:=fa4,24.0:=fb4,34.0:="fc4","44":="d4",<<"54">>:="e4",{["04"]}:="14"} = M2,
+
+    #{15:=a5,25:=b5,35:="c5","45":="d5",<<"55">>:="e5",{["05"]}:="15"} = M3,
+    #{16:=a6,26:=b6,36:="c6","46":="d6",<<"56">>:="e6",{["06"]}:="16"} = M3,
+    #{17:=a7,27:=b7,37:="c7","47":="d7",<<"57">>:="e7",{["07"]}:="17"} = M3,
+    #{18:=a8,28:=b8,38:="c8","48":="d8",<<"58">>:="e8",{["08"]}:="18"} = M3,
+    #{19:=a9,29:=b9,39:="c9","49":="d9",<<"59">>:="e9",{["09"]}:="19"} = M3,
+
+    #{10.0:=fa0,20.0:=fb0,30.0:="fc0","40":="d0",<<"50">>:="e0",{["00"]}:="10"} = M3,
+    #{11.0:=fa1,21.0:=fb1,31.0:="fc1","41":="d1",<<"51">>:="e1",{["01"]}:="11"} = M3,
+    #{12.0:=fa2,22.0:=fb2,32.0:="fc2","42":="d2",<<"52">>:="e2",{["02"]}:="12"} = M3,
+    #{13.0:=fa3,23.0:=fb3,33.0:="fc3","43":="d3",<<"53">>:="e3",{["03"]}:="13"} = M3,
+    #{14.0:=fa4,24.0:=fb4,34.0:="fc4","44":="d4",<<"54">>:="e4",{["04"]}:="14"} = M3,
+
+    #{15.0:=fa5,25.0:=fb5,35.0:="fc5","45":="d5",<<"55">>:="e5",{["05"]}:="15"} = M3,
+    #{16.0:=fa6,26.0:=fb6,36.0:="fc6","46":="d6",<<"56">>:="e6",{["06"]}:="16"} = M3,
+    #{17.0:=fa7,27.0:=fb7,37.0:="fc7","47":="d7",<<"57">>:="e7",{["07"]}:="17"} = M3,
+    #{18.0:=fa8,28.0:=fb8,38.0:="fc8","48":="d8",<<"58">>:="e8",{["08"]}:="18"} = M3,
+    #{19.0:=fa9,29.0:=fb9,39.0:="fc9","49":="d9",<<"59">>:="e9",{["09"]}:="19"} = M3,
+
+    #{36893488147419103232:=big1,67108863:=big8,"45":="d5",<<"55">>:="e5",{["05"]}:="15"} = M3,
+    #{147573952589676412928:=big3,8589934592:=big6,"46":="d6",<<"56">>:="e6",{["06"]}:="16"} = M3,
+    #{4294967296:=big5,18446744073709551616:=big4,"47":="d7",<<"57">>:="e7",{["07"]}:="17"} = M3,
+    #{4294967295:=big7,73786976294838206464:=big2,"48":="d8",<<"58">>:="e8",{["08"]}:="18"} = M3,
+
+    ok.
+
+
+t_map_size(Config) when is_list(Config) ->
+    0 = map_size(#{}),
+    1 = map_size(#{a=>1}),
+    1 = map_size(#{a=>"wat"}),
+    2 = map_size(#{a=>1, b=>2}),
+    3 = map_size(#{a=>1, b=>2, b=>"3","33"=><<"n">>}),
+
+    true = map_is_size(#{a=>1}, 1),
+    true = map_is_size(#{a=>1, a=>2}, 1),
+    M = #{ "a" => 1, "b" => 2},
+    true  = map_is_size(M, 2),
+    false = map_is_size(M, 3),
+    true  = map_is_size(M#{ "a" => 2}, 2),
+    false = map_is_size(M#{ "c" => 2}, 2),
+
+    Ks = [build_key(fun(K) -> <<1,K:32,1>> end,I)||I<-lists:seq(1,100)],
+    ok = build_and_check_size(Ks,0,#{}),
+
+    %% try deep collisions
+    %% statistically we get another subtree at 50k -> 100k elements
+    %% Try to be nice and don't use too much memory in the testcase,
+
+    N  = 500000,
+    Is = lists:seq(1,N),
+    N  = map_size(maps:from_list([{I,I}||I<-Is])),
+    N  = map_size(maps:from_list([{<<I:32>>,I}||I<-Is])),
+    N  = map_size(maps:from_list([{integer_to_list(I),I}||I<-Is])),
+    N  = map_size(maps:from_list([{float(I),I}||I<-Is])),
+
+    %% Error cases.
+    do_badmap(fun(T) ->
+                    {'EXIT',{{badmap,T},_}} =
+                      (catch map_size(T))
+              end),
+    ok.
+
+build_and_check_size([K|Ks],N,M0) ->
+    N = map_size(M0),
+    M1 = M0#{ K => K },
+    build_and_check_size(Ks,N + 1,M1);
+build_and_check_size([],N,M) ->
+    N = map_size(M),
+    ok.
+
+map_is_size(M,N) when map_size(M) =:= N -> true;
+map_is_size(_,_) -> false.
+
+t_is_map(Config) when is_list(Config) ->
+    true = is_map(#{}),
+    true = is_map(#{a=>1}),
+    false = is_map({a,b}),
+    false = is_map(x),
+    if is_map(#{}) -> ok end,
+    if is_map(#{b=>1}) -> ok end,
+    if not is_map([1,2,3]) -> ok end,
+    if not is_map(x) -> ok end,
+    ok.
+
+% test map updates without matching
+t_update_literals_large(Config) when is_list(Config) ->
+    Map = #{ 10=>a0,20=>b0,30=>"c0","40"=>"d0",<<"50">>=>"e0",{["00"]}=>"10",
+                11=>a1,21=>b1,31=>"c1","41"=>"d1",<<"51">>=>"e1",{["01"]}=>"11",
+                12=>a2,22=>b2,32=>"c2","42"=>"d2",<<"52">>=>"e2",{["02"]}=>"12",
+                13=>a3,23=>b3,33=>"c3","43"=>"d3",<<"53">>=>"e3",{["03"]}=>"13",
+                14=>a4,24=>b4,34=>"c4","44"=>"d4",<<"54">>=>"e4",{["04"]}=>"14",
+
+                15=>a5,25=>b5,35=>"c5","45"=>"d5",<<"55">>=>"e5",{["05"]}=>"15",
+                16=>a6,26=>b6,36=>"c6","46"=>"d6",<<"56">>=>"e6",{["06"]}=>"16",
+                17=>a7,27=>b7,37=>"c7","47"=>"d7",<<"57">>=>"e7",{["07"]}=>"17",
+                18=>a8,28=>b8,38=>"c8","48"=>"d8",<<"58">>=>"e8",{["08"]}=>"18",
+                19=>a9,29=>b9,39=>"c9","49"=>"d9",<<"59">>=>"e9",{["09"]}=>"19",
+
+                10.0=>fa0,20.0=>fb0,30.0=>"fc0",
+                11.0=>fa1,21.0=>fb1,31.0=>"fc1",
+                12.0=>fa2,22.0=>fb2,32.0=>"fc2",
+                13.0=>fa3,23.0=>fb3,33.0=>"fc3",
+                14.0=>fa4,24.0=>fb4,34.0=>"fc4",
+
+                15.0=>fa5,25.0=>fb5,35.0=>"fc5",
+                16.0=>fa6,26.0=>fb6,36.0=>"fc6",
+                17.0=>fa7,27.0=>fb7,37.0=>"fc7",
+                18.0=>fa8,28.0=>fb8,38.0=>"fc8",
+                19.0=>fa9,29.0=>fb9,39.0=>"fc9",
+
+                #{ one => small, map => key } => "small map key 1",
+                #{ second => small, map => key } => "small map key 2",
+                #{ third => small, map => key } => "small map key 3",
+
+                #{ 10=>a0,20=>b0,30=>"c0","40"=>"d0",<<"50">>=>"e0",{["00"]}=>"10",
+                   11=>a1,21=>b1,31=>"c1","41"=>"d1",<<"51">>=>"e1",{["01"]}=>"11",
+                   12=>a2,22=>b2,32=>"c2","42"=>"d2",<<"52">>=>"e2",{["02"]}=>"12",
+                   13=>a3,23=>b3,33=>"c3","43"=>"d3",<<"53">>=>"e3",{["03"]}=>"13",
+                   14=>a4,24=>b4,34=>"c4","44"=>"d4",<<"54">>=>"e4",{["04"]}=>"14",
+
+                   15=>a5,25=>b5,35=>"c5","45"=>"d5",<<"55">>=>"e5",{["05"]}=>"15",
+                   16=>a6,26=>b6,36=>"c6","46"=>"d6",<<"56">>=>"e6",{["06"]}=>"16",
+                   17=>a7,27=>b7,37=>"c7","47"=>"d7",<<"57">>=>"e7",{["07"]}=>"17",
+                   18=>a8,28=>b8,38=>"c8","48"=>"d8",<<"58">>=>"e8",{["08"]}=>"18",
+                   19=>a9,29=>b9,39=>"c9","49"=>"d9",<<"59">>=>"e9",{["09"]}=>"19" } => "large map key 1",
+
+                #{ 10=>a0,20=>b0,30=>"c0","40"=>"d0",<<"50">>=>"e0",{["00"]}=>"10",
+                   11=>a1,21=>b1,31=>"c1","41"=>"d1",<<"51">>=>"e1",{["01"]}=>"11",
+                   12=>a2,22=>b2,32=>"c2","42"=>"d2",<<"52">>=>"e2",{["02"]}=>"12",
+                   13=>a3,23=>b3,33=>"c3","43"=>"d3",<<"53">>=>"e3",{["03"]}=>"13",
+                   14=>a4,24=>b4,34=>"c4","44"=>"d4",<<"54">>=>"e4",{["04"]}=>"14",
+
+                   15=>a5,25=>b5,35=>"c5","45"=>"d5",<<"55">>=>"e5",{["05"]}=>"15",
+                   k16=>a6,k26=>b6,k36=>"c6","46"=>"d6",<<"56">>=>"e6",{["06"]}=>"16",
+                   17=>a7,27=>b7,37=>"c7","47"=>"d7",<<"57">>=>"e7",{["07"]}=>"17",
+                   18=>a8,28=>b8,38=>"c8","48"=>"d8",<<"58">>=>"e8",{["08"]}=>"18",
+                   19=>a9,29=>b9,39=>"c9","49"=>"d9",<<"59">>=>"e9",{["09"]}=>"19" } => "large map key 2" },
+
+    #{x:="d",q:="4"} = loop_update_literals_x_q(Map, [
+		{"a","1"},{"b","2"},{"c","3"},{"d","4"}
+	]),
+    ok.
+
+t_update_literals(Config) when is_list(Config) ->
+    Map = #{x=>1,y=>2,z=>3,q=>4},
+    #{x:="d",q:="4"} = loop_update_literals_x_q(Map, [
+		{"a","1"},{"b","2"},{"c","3"},{"d","4"}
+	]),
+    ok.
+
+
+loop_update_literals_x_q(Map, []) -> Map;
+loop_update_literals_x_q(Map, [{X,Q}|Vs]) ->
+    loop_update_literals_x_q(Map#{q=>Q,x=>X},Vs).
+
+% test map updates with matching
+t_match_and_update_literals(Config) when is_list(Config) ->
+    Map = #{ x=>0,y=>"untouched",z=>"also untouched",q=>1,
+             #{ "one" => small, map => key } => "small map key 1" },
+    #{x:=16,q:=21,y:="untouched",z:="also untouched"} = loop_match_and_update_literals_x_q(Map, [
+	    {1,2},{3,4},{5,6},{7,8}
+	]),
+    M0 = #{ "hi" => "hello", int => 3, <<"key">> => <<"value">>,
+	    4 => number, 18446744073709551629 => wat},
+    M1 = #{},
+    M2 = M1#{ "hi" => "hello", int => 3, <<"key">> => <<"value">>,
+	4 => number, 18446744073709551629 => wat},
+    M0 = M2,
+
+    #{ 4 := another_number, int := 3 } = M2#{ 4 => another_number },
+    ok.
+
+t_match_and_update_literals_large(Config) when is_list(Config) ->
+    Map = #{ 10=>a0,20=>b0,30=>"c0","40"=>"d0",<<"50">>=>"e0",{["00"]}=>"10",
+                11=>a1,21=>b1,31=>"c1","41"=>"d1",<<"51">>=>"e1",{["01"]}=>"11",
+                12=>a2,22=>b2,32=>"c2","42"=>"d2",<<"52">>=>"e2",{["02"]}=>"12",
+                13=>a3,23=>b3,33=>"c3","43"=>"d3",<<"53">>=>"e3",{["03"]}=>"13",
+                14=>a4,24=>b4,34=>"c4","44"=>"d4",<<"54">>=>"e4",{["04"]}=>"14",
+
+                15=>a5,25=>b5,35=>"c5","45"=>"d5",<<"55">>=>"e5",{["05"]}=>"15",
+                16=>a6,26=>b6,36=>"c6","46"=>"d6",<<"56">>=>"e6",{["06"]}=>"16",
+                17=>a7,27=>b7,37=>"c7","47"=>"d7",<<"57">>=>"e7",{["07"]}=>"17",
+                18=>a8,28=>b8,38=>"c8","48"=>"d8",<<"58">>=>"e8",{["08"]}=>"18",
+                19=>a9,29=>b9,39=>"c9","49"=>"d9",<<"59">>=>"e9",{["09"]}=>"19",
+
+                10.0=>fa0,20.0=>fb0,30.0=>"fc0",
+                11.0=>fa1,21.0=>fb1,31.0=>"fc1",
+                12.0=>fa2,22.0=>fb2,32.0=>"fc2",
+                13.0=>fa3,23.0=>fb3,33.0=>"fc3",
+                14.0=>fa4,24.0=>fb4,34.0=>"fc4",
+
+                15.0=>fa5,25.0=>fb5,35.0=>"fc5",
+                16.0=>fa6,26.0=>fb6,36.0=>"fc6",
+                17.0=>fa7,27.0=>fb7,37.0=>"fc7",
+                18.0=>fa8,28.0=>fb8,38.0=>"fc8",
+                19.0=>fa9,29.0=>fb9,39.0=>"fc9",
+
+                x=>0,y=>"untouched",z=>"also untouched",q=>1,
+
+                #{ "one" => small, map => key } => "small map key 1",
+                #{ second => small, map => key } => "small map key 2",
+                #{ third => small, map => key } => "small map key 3",
+
+                #{ 10=>a0,20=>b0,30=>"c0","40"=>"d0",<<"50">>=>"e0",{["00"]}=>"10",
+                   11=>a1,21=>b1,31=>"c1","41"=>"d1",<<"51">>=>"e1",{["01"]}=>"11",
+                   12=>a2,22=>b2,32=>"c2","42"=>"d2",<<"52">>=>"e2",{["02"]}=>"12",
+                   13=>a3,23=>b3,33=>"c3","43"=>"d3",<<"53">>=>"e3",{["03"]}=>"13",
+                   14=>a4,24=>b4,34=>"c4","44"=>"d4",<<"54">>=>"e4",{["04"]}=>"14",
+
+                   15=>a5,25=>b5,35=>"c5","45"=>"d5",<<"55">>=>"e5",{["05"]}=>"15",
+                   16=>a6,26=>b6,36=>"c6","46"=>"d6",<<"56">>=>"e6",{["06"]}=>"16",
+                   17=>a7,27=>b7,37=>"c7","47"=>"d7",<<"57">>=>"e7",{["07"]}=>"17",
+                   18=>a8,28=>b8,38=>"c8","48"=>"d8",<<"58">>=>"e8",{["08"]}=>"18",
+                   19=>a9,29=>b9,39=>"c9","49"=>"d9",<<"59">>=>"e9",{["09"]}=>"19" } => "large map key 1",
+
+                #{ 10=>a0,20=>b0,30=>"c0","40"=>"d0",<<"50">>=>"e0",{["00"]}=>"10",
+                   11=>a1,21=>b1,31=>"c1","41"=>"d1",<<"51">>=>"e1",{["01"]}=>"11",
+                   12=>a2,22=>b2,32=>"c2","42"=>"d2",<<"52">>=>"e2",{["02"]}=>"12",
+                   13=>a3,23=>b3,33=>"c3","43"=>"d3",<<"53">>=>"e3",{["03"]}=>"13",
+                   14=>a4,24=>b4,34=>"c4","44"=>"d4",<<"54">>=>"e4",{["04"]}=>"14",
+
+                   15=>a5,25=>b5,35=>"c5","45"=>"d5",<<"55">>=>"e5",{["05"]}=>"15",
+                   k16=>a6,k26=>b6,k36=>"c6","46"=>"d6",<<"56">>=>"e6",{["06"]}=>"16",
+                   17=>a7,27=>b7,37=>"c7","47"=>"d7",<<"57">>=>"e7",{["07"]}=>"17",
+                   18=>a8,28=>b8,38=>"c8","48"=>"d8",<<"58">>=>"e8",{["08"]}=>"18",
+                   19=>a9,29=>b9,39=>"c9","49"=>"d9",<<"59">>=>"e9",{["09"]}=>"19" } => "large map key 2" },
+
+    #{x:=16,q:=21,y:="untouched",z:="also untouched"} = loop_match_and_update_literals_x_q(Map, [
+	    {1,2},{3,4},{5,6},{7,8}
+	]),
+    M0 = Map#{ "hi" => "hello", int => 3, <<"key">> => <<"value">>,
+                  4 => number, 18446744073709551629 => wat},
+    M1 = Map#{},
+    M2 = M1#{ "hi" => "hello", int => 3, <<"key">> => <<"value">>,
+              4 => number, 18446744073709551629 => wat},
+    M0 = M2,
+
+    #{ 4 := another_number, int := 3 } = M2#{ 4 => another_number },
+    ok.
+
+
+loop_match_and_update_literals_x_q(Map, []) -> Map;
+loop_match_and_update_literals_x_q(#{ q:=Q0, x:=X0,
+                                     #{ "one" => small, map => key } := "small map key 1" } = Map, [{X,Q}|Vs]) ->
+    loop_match_and_update_literals_x_q(Map#{q=>Q0+Q,x=>X0+X},Vs).
+
+
+t_update_map_expressions(Config) when is_list(Config) ->
+    M = maps:new(),
+    #{ a := 1 } = M#{a => 1},
+
+    #{ b := 2 } = (maps:new())#{ b => 2 },
+
+    #{ a :=42, b:=42, c:=42 } = (maps:from_list([{a,1},{b,2},{c,3}]))#{ a := 42, b := 42, c := 42 },
+    #{ "a" :=1, "b":=42, "c":=42 } = (maps:from_list([{"a",1},{"b",2}]))#{ "b" := 42, "c" => 42 },
+    Ks = lists:seq($a,$z),
+    #{ "aa" := {$a,$a}, "ac":=41, "dc":=42 } =
+        (maps:from_list([{[K1,K2],{K1,K2}}|| K1 <- Ks, K2 <- Ks]))#{ "ac" := 41, "dc" => 42 },
+
+    %% Error cases.
+    do_badmap(fun(T) ->
+		      {'EXIT',{{badmap,T},_}} =
+			  (catch (T)#{a:=42,b=>2})
+	      end),
+    ok.
+
+t_update_assoc(Config) when is_list(Config) ->
+    M0 = #{1=>a,2=>b,3.0=>c,4=>d,5=>e},
+
+    M1 = M0#{1=>42,2=>100,4=>[a,b,c]},
+    #{1:=42,2:=100,3.0:=c,4:=[a,b,c],5:=e} = M1,
+    #{1:=42,2:=b,4:=d,5:=e,2.0:=100,3.0:=c,4.0:=[a,b,c]} = M0#{1.0=>float,1:=42,2.0=>wrong,2.0=>100,4.0=>[a,b,c]},
+
+    M2 = M0#{3.0=>new},
+    #{1:=a,2:=b,3.0:=new,4:=d,5:=e} = M2,
+    M2 = M0#{3.0:=wrong,3.0=>new},
+
+    %% Errors cases.
+    do_badmap(fun(T) ->
+		      {'EXIT',{{badmap,T},_}} =
+			  (catch T#{nonexisting=>val})
+	      end),
+    ok.
+
+
+t_update_assoc_large(Config) when is_list(Config) ->
+    M0 = #{ 10=>a0,20=>b0,30=>"c0","40"=>"d0",<<"50">>=>"e0",{["00"]}=>"10",
+               11=>a1,21=>b1,31=>"c1","41"=>"d1",<<"51">>=>"e1",{["01"]}=>"11",
+               12=>a2,22=>b2,32=>"c2","42"=>"d2",<<"52">>=>"e2",{["02"]}=>"12",
+               13=>a3,23=>b3,33=>"c3","43"=>"d3",<<"53">>=>"e3",{["03"]}=>"13",
+               14=>a4,24=>b4,34=>"c4","44"=>"d4",<<"54">>=>"e4",{["04"]}=>"14",
+
+               15=>a5,25=>b5,35=>"c5","45"=>"d5",<<"55">>=>"e5",{["05"]}=>"15",
+               16=>a6,26=>b6,36=>"c6","46"=>"d6",<<"56">>=>"e6",{["06"]}=>"16",
+               17=>a7,27=>b7,37=>"c7","47"=>"d7",<<"57">>=>"e7",{["07"]}=>"17",
+               18=>a8,28=>b8,38=>"c8","48"=>"d8",<<"58">>=>"e8",{["08"]}=>"18",
+               19=>a9,29=>b9,39=>"c9","49"=>"d9",<<"59">>=>"e9",{["09"]}=>"19",
+
+               10.0=>fa0,20.0=>fb0,30.0=>"fc0",
+               11.0=>fa1,21.0=>fb1,31.0=>"fc1",
+               12.0=>fa2,22.0=>fb2,32.0=>"fc2",
+               13.0=>fa3,23.0=>fb3,33.0=>"fc3",
+               14.0=>fa4,24.0=>fb4,34.0=>"fc4",
+
+               15.0=>fa5,25.0=>fb5,35.0=>"fc5",
+               16.0=>fa6,26.0=>fb6,36.0=>"fc6",
+               17.0=>fa7,27.0=>fb7,37.0=>"fc7",
+               18.0=>fa8,28.0=>fb8,38.0=>"fc8",
+               19.0=>fa9,29.0=>fb9,39.0=>"fc9",
+
+               #{ one => small, map => key } => "small map key 1",
+               #{ second => small, map => key } => "small map key 2",
+               #{ third => small, map => key } => "small map key 3",
+
+               #{ 10=>a0,20=>b0,30=>"c0","40"=>"d0",<<"50">>=>"e0",{["00"]}=>"10",
+                  11=>a1,21=>b1,31=>"c1","41"=>"d1",<<"51">>=>"e1",{["01"]}=>"11",
+                  12=>a2,22=>b2,32=>"c2","42"=>"d2",<<"52">>=>"e2",{["02"]}=>"12",
+                  13=>a3,23=>b3,33=>"c3","43"=>"d3",<<"53">>=>"e3",{["03"]}=>"13",
+                  14=>a4,24=>b4,34=>"c4","44"=>"d4",<<"54">>=>"e4",{["04"]}=>"14",
+
+                  15=>a5,25=>b5,35=>"c5","45"=>"d5",<<"55">>=>"e5",{["05"]}=>"15",
+                  16=>a6,26=>b6,36=>"c6","46"=>"d6",<<"56">>=>"e6",{["06"]}=>"16",
+                  17=>a7,27=>b7,37=>"c7","47"=>"d7",<<"57">>=>"e7",{["07"]}=>"17",
+                  18=>a8,28=>b8,38=>"c8","48"=>"d8",<<"58">>=>"e8",{["08"]}=>"18",
+                  19=>a9,29=>b9,39=>"c9","49"=>"d9",<<"59">>=>"e9",{["09"]}=>"19" } => "large map key 1",
+
+               #{ 10=>a0,20=>b0,30=>"c0","40"=>"d0",<<"50">>=>"e0",{["00"]}=>"10",
+                  11=>a1,21=>b1,31=>"c1","41"=>"d1",<<"51">>=>"e1",{["01"]}=>"11",
+                  12=>a2,22=>b2,32=>"c2","42"=>"d2",<<"52">>=>"e2",{["02"]}=>"12",
+                  13=>a3,23=>b3,33=>"c3","43"=>"d3",<<"53">>=>"e3",{["03"]}=>"13",
+                  14=>a4,24=>b4,34=>"c4","44"=>"d4",<<"54">>=>"e4",{["04"]}=>"14",
+
+                  15=>a5,25=>b5,35=>"c5","45"=>"d5",<<"55">>=>"e5",{["05"]}=>"15",
+                  k16=>a6,k26=>b6,k36=>"c6","46"=>"d6",<<"56">>=>"e6",{["06"]}=>"16",
+                  17=>a7,27=>b7,37=>"c7","47"=>"d7",<<"57">>=>"e7",{["07"]}=>"17",
+                  18=>a8,28=>b8,38=>"c8","48"=>"d8",<<"58">>=>"e8",{["08"]}=>"18",
+                  19=>a9,29=>b9,39=>"c9","49"=>"d9",<<"59">>=>"e9",{["09"]}=>"19" } => "large map key 2" },
+
+
+    M1 = M0#{1=>42,2=>100,4=>[a,b,c]},
+    #{1:=42,2:=100,10.0:=fa0,4:=[a,b,c],25:=b5} = M1,
+    #{ 10:=43, 24:=b4, 15:=a5, 35:="c5", 2.0:=100, 13.0:=fa3, 4.0:=[a,b,c]} =
+        M0#{1.0=>float,10:=43,2.0=>wrong,2.0=>100,4.0=>[a,b,c]},
+
+    M2 = M0#{13.0=>new},
+    #{10:=a0,20:=b0,13.0:=new,"40":="d0",<<"50">>:="e0"} = M2,
+    M2 = M0#{13.0:=wrong,13.0=>new},
+
+    ok.
+
+t_update_exact(Config) when is_list(Config) ->
+    M0 = #{1=>a,2=>b,3.0=>c,4=>d,5=>e},
+
+    M1 = M0#{1:=42,2:=100,4:=[a,b,c]},
+    #{1:=42,2:=100,3.0:=c,4:=[a,b,c],5:=e} = M1,
+    M1 = M0#{1:=wrong,1=>42,2=>wrong,2:=100,4:=[a,b,c]},
+
+    M2 = M0#{3.0:=new},
+    #{1:=a,2:=b,3.0:=new,4:=d,5:=e} = M2,
+    M2 = M0#{3.0=>wrong,3.0:=new},
+    true = M2 =/= M0#{3=>right,3.0:=new},
+    #{ 3 := right, 3.0 := new } = M0#{3=>right,3.0:=new},
+
+    M3 = #{ 1 => val},
+    #{1 := update2,1.0 := new_val4} = M3#{
+	1.0 => new_val1, 1 := update, 1=> update3,
+	1 := update2, 1.0 := new_val2, 1.0 => new_val3,
+	1.0 => new_val4 },
+
+    %% Errors cases.
+    do_badmap(fun(T) ->
+		      {'EXIT',{{badmap,T},_}} =
+			  (catch T#{nonexisting=>val})
+	      end),
+    Empty = #{},
+    {'EXIT',{{badkey,nonexisting},_}} = (catch Empty#{nonexisting:=val}),
+    {'EXIT',{{badkey,nonexisting},_}} = (catch M0#{nonexisting:=val}),
+    {'EXIT',{{badkey,1.0},_}} = (catch M0#{1.0:=v,1.0=>v2}),
+    {'EXIT',{{badkey,42},_}} = (catch M0#{42.0:=v,42:=v2}),
+    {'EXIT',{{badkey,42.0},_}} = (catch M0#{42=>v1,42.0:=v2,42:=v3}),
+
+    ok.
+
+t_update_exact_large(Config) when is_list(Config) ->
+    M0 = #{ 10=>a0,20=>b0,30=>"c0","40"=>"d0",<<"50">>=>"e0",{["00"]}=>"10",
+               11=>a1,21=>b1,31=>"c1","41"=>"d1",<<"51">>=>"e1",{["01"]}=>"11",
+               12=>a2,22=>b2,32=>"c2","42"=>"d2",<<"52">>=>"e2",{["02"]}=>"12",
+               13=>a3,23=>b3,33=>"c3","43"=>"d3",<<"53">>=>"e3",{["03"]}=>"13",
+               14=>a4,24=>b4,34=>"c4","44"=>"d4",<<"54">>=>"e4",{["04"]}=>"14",
+
+               15=>a5,25=>b5,35=>"c5","45"=>"d5",<<"55">>=>"e5",{["05"]}=>"15",
+               16=>a6,26=>b6,36=>"c6","46"=>"d6",<<"56">>=>"e6",{["06"]}=>"16",
+               17=>a7,27=>b7,37=>"c7","47"=>"d7",<<"57">>=>"e7",{["07"]}=>"17",
+               18=>a8,28=>b8,38=>"c8","48"=>"d8",<<"58">>=>"e8",{["08"]}=>"18",
+               19=>a9,29=>b9,39=>"c9","49"=>"d9",<<"59">>=>"e9",{["09"]}=>"19",
+
+               10.0=>fa0,20.0=>fb0,30.0=>"fc0",
+               11.0=>fa1,21.0=>fb1,31.0=>"fc1",
+               12.0=>fa2,22.0=>fb2,32.0=>"fc2",
+               13.0=>fa3,23.0=>fb3,33.0=>"fc3",
+               14.0=>fa4,24.0=>fb4,34.0=>"fc4",
+
+               15.0=>fa5,25.0=>fb5,35.0=>"fc5",
+               16.0=>fa6,26.0=>fb6,36.0=>"fc6",
+               17.0=>fa7,27.0=>fb7,37.0=>"fc7",
+               18.0=>fa8,28.0=>fb8,38.0=>"fc8",
+               19.0=>fa9,29.0=>fb9,39.0=>"fc9",
+
+               #{ one => small, map => key } => "small map key 1",
+               #{ second => small, map => key } => "small map key 2",
+               #{ third => small, map => key } => "small map key 3",
+
+               #{ 10=>a0,20=>b0,30=>"c0","40"=>"d0",<<"50">>=>"e0",{["00"]}=>"10",
+                  11=>a1,21=>b1,31=>"c1","41"=>"d1",<<"51">>=>"e1",{["01"]}=>"11",
+                  12=>a2,22=>b2,32=>"c2","42"=>"d2",<<"52">>=>"e2",{["02"]}=>"12",
+                  13=>a3,23=>b3,33=>"c3","43"=>"d3",<<"53">>=>"e3",{["03"]}=>"13",
+                  14=>a4,24=>b4,34=>"c4","44"=>"d4",<<"54">>=>"e4",{["04"]}=>"14",
+
+                  15=>a5,25=>b5,35=>"c5","45"=>"d5",<<"55">>=>"e5",{["05"]}=>"15",
+                  16=>a6,26=>b6,36=>"c6","46"=>"d6",<<"56">>=>"e6",{["06"]}=>"16",
+                  17=>a7,27=>b7,37=>"c7","47"=>"d7",<<"57">>=>"e7",{["07"]}=>"17",
+                  18=>a8,28=>b8,38=>"c8","48"=>"d8",<<"58">>=>"e8",{["08"]}=>"18",
+                  19=>a9,29=>b9,39=>"c9","49"=>"d9",<<"59">>=>"e9",{["09"]}=>"19" } => "large map key 1",
+
+               #{ 10=>a0,20=>b0,30=>"c0","40"=>"d0",<<"50">>=>"e0",{["00"]}=>"10",
+                  11=>a1,21=>b1,31=>"c1","41"=>"d1",<<"51">>=>"e1",{["01"]}=>"11",
+                  12=>a2,22=>b2,32=>"c2","42"=>"d2",<<"52">>=>"e2",{["02"]}=>"12",
+                  13=>a3,23=>b3,33=>"c3","43"=>"d3",<<"53">>=>"e3",{["03"]}=>"13",
+                  14=>a4,24=>b4,34=>"c4","44"=>"d4",<<"54">>=>"e4",{["04"]}=>"14",
+
+                  15=>a5,25=>b5,35=>"c5","45"=>"d5",<<"55">>=>"e5",{["05"]}=>"15",
+                  k16=>a6,k26=>b6,k36=>"c6","46"=>"d6",<<"56">>=>"e6",{["06"]}=>"16",
+                  17=>a7,27=>b7,37=>"c7","47"=>"d7",<<"57">>=>"e7",{["07"]}=>"17",
+                  18=>a8,28=>b8,38=>"c8","48"=>"d8",<<"58">>=>"e8",{["08"]}=>"18",
+                  19=>a9,29=>b9,39=>"c9","49"=>"d9",<<"59">>=>"e9",{["09"]}=>"19" } => "large map key 2" },
+
+
+    M1 = M0#{10:=42,<<"55">>:=100,10.0:=[a,b,c]},
+    #{ 10:=42,<<"55">>:=100,{["05"]}:="15",10.0:=[a,b,c],
+       #{ 10=>a0,20=>b0,30=>"c0","40"=>"d0",<<"50">>=>"e0",{["00"]}=>"10",
+          11=>a1,21=>b1,31=>"c1","41"=>"d1",<<"51">>=>"e1",{["01"]}=>"11",
+          12=>a2,22=>b2,32=>"c2","42"=>"d2",<<"52">>=>"e2",{["02"]}=>"12",
+          13=>a3,23=>b3,33=>"c3","43"=>"d3",<<"53">>=>"e3",{["03"]}=>"13",
+          14=>a4,24=>b4,34=>"c4","44"=>"d4",<<"54">>=>"e4",{["04"]}=>"14",
+
+          15=>a5,25=>b5,35=>"c5","45"=>"d5",<<"55">>=>"e5",{["05"]}=>"15",
+          16=>a6,26=>b6,36=>"c6","46"=>"d6",<<"56">>=>"e6",{["06"]}=>"16",
+          17=>a7,27=>b7,37=>"c7","47"=>"d7",<<"57">>=>"e7",{["07"]}=>"17",
+          18=>a8,28=>b8,38=>"c8","48"=>"d8",<<"58">>=>"e8",{["08"]}=>"18",
+          19=>a9,29=>b9,39=>"c9","49"=>"d9",<<"59">>=>"e9",{["09"]}=>"19" } := "large map key 1" } = M1,
+
+    M1 = M0#{10:=wrong,10=>42,<<"55">>=>wrong,<<"55">>:=100,10.0:=[a,b,c]},
+
+    M2 = M0#{13.0:=new},
+    #{10:=a0,20:=b0,13.0:=new} = M2,
+    M2 = M0#{13.0=>wrong,13.0:=new},
+
+    %% Errors cases.
+    {'EXIT',{{badkey,nonexisting},_}} = (catch M0#{nonexisting:=val}),
+    {'EXIT',{{badkey,1.0},_}} = (catch M0#{1.0:=v,1.0=>v2}),
+    {'EXIT',{{badkey,42},_}} = (catch M0#{42.0:=v,42:=v2}),
+    {'EXIT',{{badkey,42.0},_}} = (catch M0#{42=>v1,42.0:=v2,42:=v3}),
+
+    ok.
+
+t_update_deep(Config) when is_list(Config) ->
+    N = 250000,
+    M0 = maps:from_list([{integer_to_list(I),a}||I<-lists:seq(1,N)]),
+    #{ "1" := a, "10" := a, "100" := a, "1000" := a, "10000" := a } = M0,
+
+    M1 = M0#{ "1" := b, "10" := b, "100" := b, "1000" := b, "10000" := b },
+    #{ "1" := a, "10" := a, "100" := a, "1000" := a, "10000" := a } = M0,
+    #{ "1" := b, "10" := b, "100" := b, "1000" := b, "10000" := b } = M1,
+
+    M2 = M0#{ "1" => c, "10" => c, "100" => c, "1000" => c, "10000" => c },
+    #{ "1" := a, "10" := a, "100" := a, "1000" := a, "10000" := a } = M0,
+    #{ "1" := b, "10" := b, "100" := b, "1000" := b, "10000" := b } = M1,
+    #{ "1" := c, "10" := c, "100" := c, "1000" := c, "10000" := c } = M2,
+
+    M3 = M2#{ "n1" => d, "n10" => d, "n100" => d, "n1000" => d, "n10000" => d },
+    #{  "1" := a,  "10" := a,  "100" := a,  "1000" := a,  "10000" := a } = M0,
+    #{  "1" := b,  "10" := b,  "100" := b,  "1000" := b,  "10000" := b } = M1,
+    #{  "1" := c,  "10" := c,  "100" := c,  "1000" := c,  "10000" := c } = M2,
+    #{  "1" := c,  "10" := c,  "100" := c,  "1000" := c,  "10000" := c } = M3,
+    #{ "n1" := d, "n10" := d, "n100" := d, "n1000" := d, "n10000" := d } = M3,
+    ok.
+
+t_guard_bifs(Config) when is_list(Config) ->
+    true   = map_guard_head(#{a=>1}),
+    false  = map_guard_head([]),
+    true   = map_guard_body(#{a=>1}),
+    false  = map_guard_body({}),
+    true   = map_guard_pattern(#{a=>1, <<"hi">> => "hi" }),
+    false  = map_guard_pattern("list"),
+    ok.
+
+map_guard_head(M) when is_map(M) -> true;
+map_guard_head(_) -> false.
+
+map_guard_body(M) -> is_map(M).
+
+map_guard_pattern(#{}) -> true;
+map_guard_pattern(_)   -> false.
+
+t_guard_sequence(Config) when is_list(Config) ->
+	{1, "a"} = map_guard_sequence_1(#{seq=>1,val=>"a"}),
+	{2, "b"} = map_guard_sequence_1(#{seq=>2,val=>"b"}),
+	{3, "c"} = map_guard_sequence_1(#{seq=>3,val=>"c"}),
+	{4, "d"} = map_guard_sequence_1(#{seq=>4,val=>"d"}),
+	{5, "e"} = map_guard_sequence_1(#{seq=>5,val=>"e"}),
+
+	{1,M1}       = map_guard_sequence_2(M1 = #{a=>3}),
+	{2,M2}       = map_guard_sequence_2(M2 = #{a=>4, b=>4}),
+	{3,gg,M3}    = map_guard_sequence_2(M3 = #{a=>gg, b=>4}),
+	{4,sc,sc,M4} = map_guard_sequence_2(M4 = #{a=>sc, b=>3, c=>sc2}),
+	{5,kk,kk,M5} = map_guard_sequence_2(M5 = #{a=>kk, b=>other, c=>sc2}),
+
+	%% error case
+	{'EXIT',{function_clause,_}} = (catch map_guard_sequence_1(#{seq=>6,val=>"e"})),
+	{'EXIT',{function_clause,_}} = (catch map_guard_sequence_2(#{b=>5})),
+	ok.
+
+t_guard_sequence_large(Config) when is_list(Config) ->
+    M0 = #{ 10=>a0,20=>b0,30=>"c0","40"=>"d0",<<"50">>=>"e0",{["00",03]}=>"10",
+               11=>a1,21=>b1,31=>"c1","41"=>"d1",<<"51">>=>"e1",{["01",03]}=>"11",
+               12=>a2,22=>b2,32=>"c2","42"=>"d2",<<"52">>=>"e2",{["02",03]}=>"12",
+               13=>a3,23=>b3,33=>"c3","43"=>"d3",<<"53">>=>"e3",{["03",03]}=>"13",
+               14=>a4,24=>b4,34=>"c4","44"=>"d4",<<"54">>=>"e4",{["04",03]}=>"14",
+
+               15=>a5,25=>b5,35=>"c5","45"=>"d5",<<"55">>=>"e5",{["05",03]}=>"15",
+               16=>a6,26=>b6,36=>"c6","46"=>"d6",<<"56">>=>"e6",{["06",03]}=>"16",
+               17=>a7,27=>b7,37=>"c7","47"=>"d7",<<"57">>=>"e7",{["07",03]}=>"17",
+               18=>a8,28=>b8,38=>"c8","48"=>"d8",<<"58">>=>"e8",{["08",03]}=>"18",
+               19=>a9,29=>b9,39=>"c9","49"=>"d9",<<"59">>=>"e9",{["09",03]}=>"19",
+
+               10.0=>fa0,20.0=>fb0,30.0=>"fc0",
+               11.0=>fa1,21.0=>fb1,31.0=>"fc1",
+               12.0=>fa2,22.0=>fb2,32.0=>"fc2",
+               13.0=>fa3,23.0=>fb3,33.0=>"fc3",
+               14.0=>fa4,24.0=>fb4,34.0=>"fc4",
+
+               15.0=>fa5,25.0=>fb5,35.0=>"fc5",
+               16.0=>fa6,26.0=>fb6,36.0=>"fc6",
+               17.0=>fa7,27.0=>fb7,37.0=>"fc7",
+               18.0=>fa8,28.0=>fb8,38.0=>"fc8",
+               19.0=>fa9,29.0=>fb9,39.0=>"fc9",
+
+               #{ one => small, map => key } => "small map key 1",
+               #{ second => small, map => key } => "small map key 2",
+               #{ third => small, map => key } => "small map key 3",
+
+               #{ 10=>a0,20=>b0,30=>"c0","40"=>"d0",<<"50">>=>"e0",{["00"]}=>"10",
+                  11=>a1,21=>b1,31=>"c1","41"=>"d1",<<"51">>=>"e1",{["01"]}=>"11",
+                  12=>a2,22=>b2,32=>"c2","42"=>"d2",<<"52">>=>"e2",{["02"]}=>"12",
+                  13=>a3,23=>b3,33=>"c3","43"=>"d3",<<"53">>=>"e3",{["03"]}=>"13",
+                  14=>a4,24=>b4,34=>"c4","44"=>"d4",<<"54">>=>"e4",{["04"]}=>"14",
+
+                  15=>a5,25=>b5,35=>"c5","45"=>"d5",<<"55">>=>"e5",{["05"]}=>"15",
+                  16=>a6,26=>b6,36=>"c6","46"=>"d6",<<"56">>=>"e6",{["06"]}=>"16",
+                  17=>a7,27=>b7,37=>"c7","47"=>"d7",<<"57">>=>"e7",{["07"]}=>"17",
+                  18=>a8,28=>b8,38=>"c8","48"=>"d8",<<"58">>=>"e8",{["08"]}=>"18",
+                  19=>a9,29=>b9,39=>"c9","49"=>"d9",<<"59">>=>"e9",{["09"]}=>"19" } => "large map key 1",
+
+               #{ 10=>a0,20=>b0,30=>"c0","40"=>"d0",<<"50">>=>"e0",{["00"]}=>"10",
+                  11=>a1,21=>b1,31=>"c1","41"=>"d1",<<"51">>=>"e1",{["01"]}=>"11",
+                  12=>a2,22=>b2,32=>"c2","42"=>"d2",<<"52">>=>"e2",{["02"]}=>"12",
+                  13=>a3,23=>b3,33=>"c3","43"=>"d3",<<"53">>=>"e3",{["03"]}=>"13",
+                  14=>a4,24=>b4,34=>"c4","44"=>"d4",<<"54">>=>"e4",{["04"]}=>"14",
+
+                  15=>a5,25=>b5,35=>"c5","45"=>"d5",<<"55">>=>"e5",{["05"]}=>"15",
+                  k16=>a6,k26=>b6,k36=>"c6","46"=>"d6",<<"56">>=>"e6",{["06"]}=>"16",
+                  17=>a7,27=>b7,37=>"c7","47"=>"d7",<<"57">>=>"e7",{["07"]}=>"17",
+                  18=>a8,28=>b8,38=>"c8","48"=>"d8",<<"58">>=>"e8",{["08"]}=>"18",
+                  19=>a9,29=>b9,39=>"c9","49"=>"d9",<<"59">>=>"e9",{["09"]}=>"19" } => "large map key 2" },
+
+	{1, "a"} = map_guard_sequence_1(M0#{seq=>1,val=>"a"}),
+	{2, "b"} = map_guard_sequence_1(M0#{seq=>2,val=>"b"}),
+	{3, "c"} = map_guard_sequence_1(M0#{seq=>3,val=>"c"}),
+	{4, "d"} = map_guard_sequence_1(M0#{seq=>4,val=>"d"}),
+	{5, "e"} = map_guard_sequence_1(M0#{seq=>5,val=>"e"}),
+
+	{1,M1}       = map_guard_sequence_2(M1 = M0#{a=>3}),
+	{2,M2}       = map_guard_sequence_2(M2 = M0#{a=>4, b=>4}),
+	{3,gg,M3}    = map_guard_sequence_2(M3 = M0#{a=>gg, b=>4}),
+	{4,sc,sc,M4} = map_guard_sequence_2(M4 = M0#{a=>sc, b=>3, c=>sc2}),
+	{5,kk,kk,M5} = map_guard_sequence_2(M5 = M0#{a=>kk, b=>other, c=>sc2}),
+
+	{'EXIT',{function_clause,_}} = (catch map_guard_sequence_1(M0#{seq=>6,val=>"e"})),
+	{'EXIT',{function_clause,_}} = (catch map_guard_sequence_2(M0#{b=>5})),
+        ok.
+
+
+map_guard_sequence_1(#{seq:=1=Seq, val:=Val}) -> {Seq,Val};
+map_guard_sequence_1(#{seq:=2=Seq, val:=Val}) -> {Seq,Val};
+map_guard_sequence_1(#{seq:=3=Seq, val:=Val}) -> {Seq,Val};
+map_guard_sequence_1(#{seq:=4=Seq, val:=Val}) -> {Seq,Val};
+map_guard_sequence_1(#{seq:=5=Seq, val:=Val}) -> {Seq,Val}.
+
+map_guard_sequence_2(#{ a:=3 }=M) -> {1, M};
+map_guard_sequence_2(#{ a:=4 }=M) -> {2, M};
+map_guard_sequence_2(#{ a:=X, a:=X, b:=4 }=M) -> {3,X,M};
+map_guard_sequence_2(#{ a:=X, a:=Y, b:=3 }=M) when X =:= Y -> {4,X,Y,M};
+map_guard_sequence_2(#{ a:=X, a:=Y }=M) when X =:= Y -> {5,X,Y,M}.
+
+
+t_guard_update(Config) when is_list(Config) ->
+    error  = map_guard_update(#{},#{}),
+    first  = map_guard_update(#{}, #{x=>first}),
+    second = map_guard_update(#{y=>old}, #{x=>second,y=>old}),
+    ok.
+
+t_guard_update_large(Config) when is_list(Config) ->
+    M0 = #{ 70=>a0,80=>b0,90=>"c0","40"=>"d0",<<"50">>=>"e0",{["00",03]}=>"10",
+               71=>a1,81=>b1,91=>"c1","41"=>"d1",<<"51">>=>"e1",{["01",03]}=>"11",
+               72=>a2,82=>b2,92=>"c2","42"=>"d2",<<"52">>=>"e2",{["02",03]}=>"12",
+               73=>a3,83=>b3,93=>"c3","43"=>"d3",<<"53">>=>"e3",{["03",03]}=>"13",
+               74=>a4,84=>b4,94=>"c4","44"=>"d4",<<"54">>=>"e4",{["04",03]}=>"14",
+
+               75=>a5,85=>b5,95=>"c5","45"=>"d5",<<"55">>=>"e5",{["05",03]}=>"15",
+               76=>a6,86=>b6,96=>"c6","46"=>"d6",<<"56">>=>"e6",{["06",03]}=>"16",
+               77=>a7,87=>b7,97=>"c7","47"=>"d7",<<"57">>=>"e7",{["07",03]}=>"17",
+               78=>a8,88=>b8,98=>"c8","48"=>"d8",<<"58">>=>"e8",{["08",03]}=>"18",
+               79=>a9,89=>b9,99=>"c9","49"=>"d9",<<"59">>=>"e9",{["09",03]}=>"19",
+
+               70.0=>fa0,80.0=>fb0,90.0=>"fc0",
+               71.0=>fa1,81.0=>fb1,91.0=>"fc1",
+               72.0=>fa2,82.0=>fb2,92.0=>"fc2",
+               73.0=>fa3,83.0=>fb3,93.0=>"fc3",
+               74.0=>fa4,84.0=>fb4,94.0=>"fc4",
+
+               75.0=>fa5,85.0=>fb5,95.0=>"fc5",
+               76.0=>fa6,86.0=>fb6,96.0=>"fc6",
+               77.0=>fa7,87.0=>fb7,97.0=>"fc7",
+               78.0=>fa8,88.0=>fb8,98.0=>"fc8",
+               79.0=>fa9,89.0=>fb9,99.0=>"fc9",
+
+               #{ one => small, map => key } => "small map key 1",
+               #{ second => small, map => key } => "small map key 2",
+               #{ third => small, map => key } => "small map key 3",
+
+               #{ 10=>a0,20=>b0,30=>"c0","40"=>"d0",<<"50">>=>"e0",{["00"]}=>"10",
+                  11=>a1,21=>b1,31=>"c1","41"=>"d1",<<"51">>=>"e1",{["01"]}=>"11",
+                  12=>a2,22=>b2,32=>"c2","42"=>"d2",<<"52">>=>"e2",{["02"]}=>"12",
+                  13=>a3,23=>b3,33=>"c3","43"=>"d3",<<"53">>=>"e3",{["03"]}=>"13",
+                  14=>a4,24=>b4,34=>"c4","44"=>"d4",<<"54">>=>"e4",{["04"]}=>"14",
+
+                  15=>a5,25=>b5,35=>"c5","45"=>"d5",<<"55">>=>"e5",{["05"]}=>"15",
+                  16=>a6,26=>b6,36=>"c6","46"=>"d6",<<"56">>=>"e6",{["06"]}=>"16",
+                  17=>a7,27=>b7,37=>"c7","47"=>"d7",<<"57">>=>"e7",{["07"]}=>"17",
+                  18=>a8,28=>b8,38=>"c8","48"=>"d8",<<"58">>=>"e8",{["08"]}=>"18",
+                  19=>a9,29=>b9,39=>"c9","49"=>"d9",<<"59">>=>"e9",{["09"]}=>"19" } => "large map key 1",
+
+               #{ 10=>a0,20=>b0,30=>"c0","40"=>"d0",<<"50">>=>"e0",{["00"]}=>"10",
+                  11=>a1,21=>b1,31=>"c1","41"=>"d1",<<"51">>=>"e1",{["01"]}=>"11",
+                  12=>a2,22=>b2,32=>"c2","42"=>"d2",<<"52">>=>"e2",{["02"]}=>"12",
+                  13=>a3,23=>b3,33=>"c3","43"=>"d3",<<"53">>=>"e3",{["03"]}=>"13",
+                  14=>a4,24=>b4,34=>"c4","44"=>"d4",<<"54">>=>"e4",{["04"]}=>"14",
+
+                  15=>a5,25=>b5,35=>"c5","45"=>"d5",<<"55">>=>"e5",{["05"]}=>"15",
+                  k16=>a6,k26=>b6,k36=>"c6","46"=>"d6",<<"56">>=>"e6",{["06"]}=>"16",
+                  17=>a7,27=>b7,37=>"c7","47"=>"d7",<<"57">>=>"e7",{["07"]}=>"17",
+                  18=>a8,28=>b8,38=>"c8","48"=>"d8",<<"58">>=>"e8",{["08"]}=>"18",
+                  19=>a9,29=>b9,39=>"c9","49"=>"d9",<<"59">>=>"e9",{["09"]}=>"19" } => "large map key 2" },
+
+
+    error  = map_guard_update(M0#{},M0#{}),
+    first  = map_guard_update(M0#{},M0#{x=>first}),
+    second = map_guard_update(M0#{y=>old}, M0#{x=>second,y=>old}),
+    ok.
+
+
+map_guard_update(M1, M2) when M1#{x=>first}  =:= M2 -> first;
+map_guard_update(M1, M2) when M1#{x=>second} =:= M2 -> second;
+map_guard_update(_, _) -> error.
+
+t_guard_receive(Config) when is_list(Config) ->
+    M0  = #{ id => 0 },
+    Pid = spawn_link(fun() -> guard_receive_loop() end),
+    Big = 36893488147419103229,
+    B1  = <<"some text">>,
+    B2  = <<"was appended">>,
+    B3  = <<B1/binary, B2/binary>>,
+
+    #{id:=1, res:=Big} = M1 = call(Pid, M0#{op=>sub,in=>{1 bsl 65, 3}}),
+    #{id:=2, res:=26}  = M2 = call(Pid, M1#{op=>idiv,in=>{53,2}}),
+    #{id:=3, res:=832} = M3 = call(Pid, M2#{op=>imul,in=>{26,32}}),
+    #{id:=4, res:=4}   = M4 = call(Pid, M3#{op=>add,in=>{1,3}}),
+    #{id:=5, res:=Big} = M5 = call(Pid, M4#{op=>sub,in=>{1 bsl 65, 3}}),
+    #{id:=6, res:=B3}  = M6 = call(Pid, M5#{op=>"append",in=>{B1,B2}}),
+    #{id:=7, res:=4}   = _  = call(Pid, M6#{op=>add,in=>{1,3}}),
+
+
+    %% update old maps and check id update
+    #{id:=2, res:=B3} = call(Pid, M1#{op=>"append",in=>{B1,B2}}),
+    #{id:=5, res:=99} = call(Pid, M4#{op=>add,in=>{33, 66}}),
+
+    %% cleanup
+    done = call(Pid, done),
+    ok.
+
+-define(t_guard_receive_large_procs, 1500).
+
+t_guard_receive_large(Config) when is_list(Config) ->
+    M = lists:foldl(fun(_,#{procs := Ps } = M) ->
+                            M#{ procs := Ps#{ spawn_link(fun() -> grecv_loop() end) => 0 }}
+                    end, #{procs => #{}, done => 0}, lists:seq(1,?t_guard_receive_large_procs)),
+    lists:foreach(fun(Pid) ->
+                          Pid ! {self(), hello}
+                  end, maps:keys(maps:get(procs,M))),
+    ok = guard_receive_large_loop(M),
+    ok.
+
+guard_receive_large_loop(#{done := ?t_guard_receive_large_procs}) ->
+    ok;
+guard_receive_large_loop(M) ->
+    receive
+        #{pid := Pid, msg := hello} ->
+            case M of
+                #{done := Count, procs := #{Pid := 150}} ->
+                    Pid ! {self(), done},
+                    guard_receive_large_loop(M#{done := Count + 1});
+                #{procs := #{Pid := Count} = Ps} ->
+                    Pid ! {self(), hello},
+                    guard_receive_large_loop(M#{procs := Ps#{Pid := Count + 1}})
+            end
+    end.
+
+grecv_loop() ->
+    receive
+        {_, done} ->
+            ok;
+        {Pid, hello} ->
+            Pid ! #{pid=>self(), msg=>hello},
+            grecv_loop()
+    end.
+
+call(Pid, M) ->
+    Pid ! {self(), M}, receive {Pid, Res} -> Res end.
+
+guard_receive_loop() ->
+    receive
+	{Pid, #{ id:=Id, op:="append", in:={X,Y}}=M} when is_binary(X), is_binary(Y) ->
+	    Pid ! {self(), M#{ id=>Id+1, res=><<X/binary,Y/binary>>}},
+	    guard_receive_loop();
+	{Pid, #{ id:=Id, op:=add, in:={X,Y}}} ->
+	    Pid ! {self(), #{ id=>Id+1, res=>X+Y}},
+	    guard_receive_loop();
+	{Pid, #{ id:=Id, op:=sub,  in:={X,Y}}=M} ->
+	    Pid ! {self(), M#{ id=>Id+1, res=>X-Y}},
+	    guard_receive_loop();
+	{Pid, #{ id:=Id, op:=idiv, in:={X,Y}}=M} ->
+	    Pid ! {self(), M#{ id=>Id+1, res=>X div Y}},
+	    guard_receive_loop();
+	{Pid, #{ id:=Id, op:=imul, in:={X,Y}}=M} ->
+	    Pid ! {self(), M#{ id=>Id+1, res=>X * Y}},
+	    guard_receive_loop();
+	{Pid, done} ->
+	    Pid ! {self(), done};
+	{Pid, Other} ->
+	    Pid ! {error, Other},
+	    guard_receive_loop()
+    end.
+
+
+t_list_comprehension(Config) when is_list(Config) ->
+    [#{k:=1},#{k:=2},#{k:=3}] = [#{k=>I} || I <- [1,2,3]],
+
+    Ks = lists:seq($a,$z),
+    Ms = [#{[K1,K2]=>{K1,K2}} || K1 <- Ks, K2 <- Ks],
+    [#{"aa" := {$a,$a}},#{"ab":={$a,$b}}|_] = Ms,
+    [#{"zz" := {$z,$z}},#{"zy":={$z,$y}}|_] = lists:reverse(Ms),
+    ok.
+
+t_guard_fun(Config) when is_list(Config) ->
+    F1 = fun
+	    (#{s:=v,v:=V})     -> {v,V};
+	    (#{s:=t,v:={V,V}}) -> {t,V};
+	    (#{s:=l,v:=[V,V]}) -> {l,V}
+    end,
+    
+    F2 = fun
+	    (#{s:=T,v:={V,V}}) -> {T,V};
+	    (#{s:=T,v:=[V,V]}) -> {T,V};
+	    (#{s:=T,v:=V})     -> {T,V}
+    end,
+    V = <<"hi">>,
+
+    {v,V} = F1(#{s=>v,v=>V}),
+    {t,V} = F1(#{s=>t,v=>{V,V}}),
+    {l,V} = F1(#{s=>l,v=>[V,V]}),
+
+    {v,V} = F2(#{s=>v,v=>V}),
+    {t,V} = F2(#{s=>t,v=>{V,V}}),
+    {l,V} = F2(#{s=>l,v=>[V,V]}),
+
+    %% error case
+    {'EXIT', {function_clause,[{?MODULE,_,[#{s:=none,v:=none}],_}|_]}} = (catch F1(#{s=>none,v=>none})),
+    ok.
+
+
+t_map_sort_literals(Config) when is_list(Config) ->
+    % test relation
+
+    %% size order
+    true  = #{ a => 1, b => 2} < #{ a => 1, b => 1, c => 1},
+    true  = #{ b => 1, a => 1} < #{ c => 1, a => 1, b => 1},
+    false = #{ c => 1, b => 1, a => 1} < #{ c => 1, a => 1},
+
+    %% key order
+    true  = #{ a => 1 } < #{ b => 1},
+    false = #{ b => 1 } < #{ a => 1},
+    true  = #{ a => 1, b => 1, c => 1 } < #{ b => 1, c => 1, d => 1},
+    true  = #{ b => 1, c => 1, d => 1 } > #{ a => 1, b => 1, c => 1},
+    true  = #{ c => 1, b => 1, a => 1 } < #{ b => 1, c => 1, d => 1},
+    true  = #{ "a" => 1 } < #{ <<"a">> => 1},
+    false = #{ <<"a">> => 1 } < #{ "a" => 1},
+    true  = #{ 1 => 1 } < #{ 1.0 => 1},
+    false = #{ 1.0 => 1 } < #{ 1 => 1},
+
+    %% value order
+    true  = #{ a => 1 } < #{ a => 2},
+    false = #{ a => 2 } < #{ a => 1},
+    false = #{ a => 2, b => 1 } < #{ a => 1, b => 3},
+    true  = #{ a => 1, b => 1 } < #{ a => 1, b => 3},
+    false = #{ a => 1 } < #{ a => 1.0},
+    false = #{ a => 1.0 } < #{ a => 1},
+
+    true  = #{ "a" => "hi", b => 134 } == #{ b => 134,"a" => "hi"},
+
+    %% large maps
+
+    M = maps:from_list([{I,I}||I <- lists:seq(1,500)]),
+
+    %% size order
+    true  = M#{ a => 1, b => 2} < M#{ a => 1, b => 1, c => 1},
+    true  = M#{ b => 1, a => 1} < M#{ c => 1, a => 1, b => 1},
+    false = M#{ c => 1, b => 1, a => 1} < M#{ c => 1, a => 1},
+
+    %% key order
+    true  = M#{ a => 1 } < M#{ b => 1},
+    false = M#{ b => 1 } < M#{ a => 1},
+    true  = M#{ a => 1, b => 1, c => 1 } < M#{ b => 1, c => 1, d => 1},
+    true  = M#{ b => 1, c => 1, d => 1 } > M#{ a => 1, b => 1, c => 1},
+    true  = M#{ c => 1, b => 1, a => 1 } < M#{ b => 1, c => 1, d => 1},
+    true  = M#{ "a" => 1 } < M#{ <<"a">> => 1},
+    false = M#{ <<"a">> => 1 } < #{ "a" => 1},
+    true  = M#{ 1 => 1 } < maps:remove(1,M#{ 1.0 => 1}),
+    false = M#{ 1.0 => 1 } < M#{ 1 => 1},
+
+    %% value order
+    true  = M#{ a => 1 } < M#{ a => 2},
+    false = M#{ a => 2 } < M#{ a => 1},
+    false = M#{ a => 2, b => 1 } < M#{ a => 1, b => 3},
+    true  = M#{ a => 1, b => 1 } < M#{ a => 1, b => 3},
+    false = M#{ a => 1 } < M#{ a => 1.0},
+    false = M#{ a => 1.0 } < M#{ a => 1},
+
+    true  = M#{ "a" => "hi", b => 134 } == M#{ b => 134,"a" => "hi"},
+
+    %% lists:sort
+
+    SortVs = [#{"a"=>1},#{a=>2},#{1=>3},#{<<"a">>=>4}],
+    [#{1:=ok},#{a:=ok},#{"a":=ok},#{<<"a">>:=ok}] = lists:sort([#{"a"=>ok},#{a=>ok},#{1=>ok},#{<<"a">>=>ok}]),
+    [#{1:=3},#{a:=2},#{"a":=1},#{<<"a">>:=4}] = lists:sort(SortVs),
+    [#{1:=3},#{a:=2},#{"a":=1},#{<<"a">>:=4}] = lists:sort(lists:reverse(SortVs)),
+    ok.
+
+t_map_equal(Config) when is_list(Config) ->
+    true  = #{} =:= #{},
+    false = #{} =:= #{a=>1},
+    false = #{a=>1} =:= #{},
+    true  = #{ "a" => "hi", b => 134 } =:= #{ b => 134,"a" => "hi"},
+
+    false = #{ a => 1 } =:= #{ a => 2},
+    false = #{ a => 2 } =:= #{ a => 1},
+    false = #{ a => 2, b => 1 } =:= #{ a => 1, b => 3},
+    false = #{ a => 1, b => 1 } =:= #{ a => 1, b => 3},
+
+    true = #{ a => 1 } =:= #{ a => 1},
+    true = #{ "a" => 2 } =:= #{ "a" => 2},
+    true = #{ "a" => 2, b => 3 } =:= #{ "a" => 2, b => 3},
+    true = #{ a => 1, b => 3, c => <<"wat">> } =:= #{ a => 1, b => 3, c=><<"wat">>},
+    ok.
+
+
+t_map_compare(Config) when is_list(Config) ->
+    Seed = {erlang:monotonic_time(),
+	    erlang:time_offset(),
+	    erlang:unique_integer()},
+    io:format("seed = ~p\n", [Seed]),
+    random:seed(Seed),
+    repeat(100, fun(_) -> float_int_compare() end, []),
+    repeat(100, fun(_) -> recursive_compare() end, []),
+    ok.
+
+float_int_compare() ->
+    Terms = numeric_keys(3),
+    %%io:format("Keys to use: ~p\n", [Terms]),
+    Pairs = lists:map(fun(K) -> list_to_tuple([{K,V} || V <- Terms]) end, Terms),
+    lists:foreach(fun(Size) ->
+			  MapGen = fun() -> map_gen(list_to_tuple(Pairs), Size) end,
+			  repeat(100, fun do_compare/1, [MapGen, MapGen])
+		  end,
+		  lists:seq(1,length(Terms))),
+    ok.
+
+numeric_keys(N) ->
+    lists:foldl(fun(_,Acc) ->
+			Int = random:uniform(N*4) - N*2,
+			Float = float(Int),
+			[Int, Float, Float * 0.99, Float * 1.01 | Acc]
+		end,
+		[],
+		lists:seq(1,N)).
+
+
+repeat(0, _, _) ->
+    ok;
+repeat(N, Fun, Arg) ->
+    Fun(Arg),
+    repeat(N-1, Fun, Arg).
+
+copy_term(T) ->
+    Papa = self(),
+    P = spawn_link(fun() -> receive Msg -> Papa ! Msg end end),
+    P ! T,
+    receive R -> R end.
+
+do_compare([Gen1, Gen2]) ->
+    M1 = Gen1(),
+    M2 = Gen2(),
+    %%io:format("Maps to compare: ~p AND ~p\n", [M1, M2]),
+    C = (M1 < M2),
+    Erlang = maps_lessthan(M1, M2),
+    C = Erlang,
+    ?CHECK(M1==M1, M1),
+
+    %% Change one key from int to float (or vice versa) and check compare
+    ML1 = maps:to_list(M1),
+    {K1,V1} = lists:nth(random:uniform(length(ML1)), ML1),
+    case K1 of
+	I when is_integer(I) ->
+	    case maps:find(float(I),M1) of
+		error ->
+		    M1f = maps:remove(I, maps:put(float(I), V1, M1)),
+		    ?CHECK(M1f > M1, [M1f, M1]);
+		_ -> ok
+	    end;
+
+	F when is_float(F), round(F) == F ->
+	    case maps:find(round(F),M1) of
+		error ->
+		    M1i = maps:remove(F, maps:put(round(F), V1, M1)),
+		    ?CHECK(M1i < M1, [M1i, M1]);
+		_ -> ok
+	    end;
+
+	_ -> ok   % skip floats with decimals
+    end,
+
+    ?CHECK(M2 == M2, [M2]).
+
+
+maps_lessthan(M1, M2) ->
+  case {maps:size(M1),maps:size(M2)} of
+      {_S,_S} ->
+	  {K1,V1} = lists:unzip(term_sort(maps:to_list(M1))),
+	  {K2,V2} = lists:unzip(term_sort(maps:to_list(M2))),
+
+	  case erts_internal:cmp_term(K1,K2) of
+	      -1 -> true;
+	      0 -> (V1 < V2);
+	      1 -> false
+	  end;
+
+      {S1, S2} ->
+	  S1 < S2
+  end.
+
+term_sort(L) ->
+    lists:sort(fun(A,B) -> erts_internal:cmp_term(A,B) =< 0 end,
+	       L).
+
+
+cmp(T1, T2, Exact) when is_tuple(T1) and is_tuple(T2) ->
+    case {size(T1),size(T2)} of
+	{_S,_S} -> cmp(tuple_to_list(T1), tuple_to_list(T2), Exact);
+	{S1,S2} when S1 < S2 -> -1;
+	{S1,S2} when S1 > S2 -> 1
+    end;
+
+cmp([H1|T1], [H2|T2], Exact) ->
+    case cmp(H1,H2, Exact) of
+	0 -> cmp(T1,T2, Exact);
+	C -> C
+    end;
+
+cmp(M1, M2, Exact) when is_map(M1) andalso is_map(M2) ->
+    cmp_maps(M1,M2,Exact);
+cmp(M1, M2, Exact) ->
+    cmp_others(M1, M2, Exact).
+
+cmp_maps(M1, M2, Exact) ->
+    case {maps:size(M1),maps:size(M2)} of
+	{_S,_S} ->
+	    {K1,V1} = lists:unzip(term_sort(maps:to_list(M1))),
+	    {K2,V2} = lists:unzip(term_sort(maps:to_list(M2))),
+
+	    case cmp(K1, K2, true) of
+		0 -> cmp(V1, V2, Exact);
+		C -> C
+	    end;
+
+	{S1,S2} when S1 < S2 -> -1;
+	{S1,S2} when S1 > S2 -> 1
+    end.
+
+cmp_others(I, F, true) when is_integer(I), is_float(F) ->
+    -1;
+cmp_others(F, I, true) when is_float(F), is_integer(I) ->
+    1;
+cmp_others(T1, T2, _) ->
+    case {T1<T2, T1==T2} of
+	{true,false} -> -1;
+	{false,true} -> 0;
+	{false,false} -> 1
+    end.
+
+map_gen(Pairs, Size) ->
+    {_,L} = lists:foldl(fun(_, {Keys, Acc}) ->
+				KI = random:uniform(size(Keys)),
+				K = element(KI,Keys),
+				KV = element(random:uniform(size(K)), K),
+				{erlang:delete_element(KI,Keys), [KV | Acc]}
+			end,
+			{Pairs, []},
+			lists:seq(1,Size)),
+
+    maps:from_list(L).
+
+
+recursive_compare() ->
+    Leafs = {atom, 17, 16.9, 17.1, [], self(), spawn(fun() -> ok end), make_ref(), make_ref()},
+    {A, B} = term_gen_recursive(Leafs, 0, 0),
+    %%io:format("Recursive term A = ~p\n", [A]),
+    %%io:format("Recursive term B = ~p\n", [B]),
+
+    ?CHECK({true,false} =:=  case do_cmp(A, B, false) of
+				 -1 -> {A<B, A>=B};
+				 0 -> {A==B, A/=B};
+				 1 -> {A>B, A=<B}
+			     end,
+	   {A,B}),
+    A2 = copy_term(A),
+    ?CHECK(A == A2, {A,A2}),
+    ?CHECK(0 =:= cmp(A, A2, false), {A,A2}),
+
+    B2 = copy_term(B),
+    ?CHECK(B == B2, {B,B2}),
+    ?CHECK(0 =:= cmp(B, B2, false), {B,B2}),
+    ok.
+
+do_cmp(A, B, Exact) ->
+    C = cmp(A, B, Exact),
+    C.
+
+%% Generate two terms {A,B} that may only differ
+%% at float vs integer types.
+term_gen_recursive(Leafs, Flags, Depth) ->
+    MaxDepth = 10,
+    Rnd = case {Flags, Depth} of
+	      {_, MaxDepth} -> % Only leafs
+		  random:uniform(size(Leafs)) + 3;
+	      {0, 0} ->        % Only containers
+		  random:uniform(3);
+	      {0,_} ->         % Anything
+		  random:uniform(size(Leafs)+3)
+	  end,
+    case Rnd of
+	1 -> % Make map
+	    Size = random:uniform(size(Leafs)),
+	    lists:foldl(fun(_, {Acc1,Acc2}) ->
+				{K1,K2} = term_gen_recursive(Leafs, Flags,
+							     Depth+1),
+				{V1,V2} = term_gen_recursive(Leafs, Flags, Depth+1),
+				{maps:put(K1,V1, Acc1), maps:put(K2,V2, Acc2)}
+			end,
+			{maps:new(), maps:new()},
+			lists:seq(1,Size));
+	2 -> % Make cons
+	    {Car1,Car2} = term_gen_recursive(Leafs, Flags, Depth+1),
+	    {Cdr1,Cdr2} = term_gen_recursive(Leafs, Flags, Depth+1),
+	    {[Car1 | Cdr1], [Car2 | Cdr2]};
+	3 -> % Make tuple
+	    Size = random:uniform(size(Leafs)),
+	    L = lists:map(fun(_) -> term_gen_recursive(Leafs, Flags, Depth+1) end,
+			  lists:seq(1,Size)),
+	    {L1, L2} = lists:unzip(L),
+	    {list_to_tuple(L1), list_to_tuple(L2)};
+
+	N -> % Make leaf
+	    case element(N-3, Leafs) of
+		I when is_integer(I) ->
+		    case random:uniform(4) of
+			1 -> {I, float(I)};
+			2 -> {float(I), I};
+			_ -> {I,I}
+		    end;
+		T -> {T,T}
+	    end
+    end.
+
+%% BIFs
+t_bif_map_get(Config) when is_list(Config) ->
+    %% small map
+    1    = maps:get(a, #{ a=> 1}),
+    2    = maps:get(b, #{ a=> 1, b => 2}),
+    "hi" = maps:get("hello", #{ a=>1, "hello" => "hi"}),
+    "tuple hi" = maps:get({1,1.0}, #{ a=>a, {1,1.0} => "tuple hi"}),
+
+    M0    = #{ k1=>"v1", <<"k2">> => <<"v3">> },
+    "v4" = maps:get(<<"k2">>, M0#{<<"k2">> => "v4"}),
+
+    %% large map
+    M1   = maps:from_list([{I,I}||I<-lists:seq(1,100)] ++
+			  [{a,1},{b,2},{"hello","hi"},{{1,1.0},"tuple hi"},
+			   {k1,"v1"},{<<"k2">>,"v3"}]),
+    1    = maps:get(a, M1),
+    2    = maps:get(b, M1),
+    "hi" = maps:get("hello", M1),
+    "tuple hi" = maps:get({1,1.0}, M1),
+    "v3" = maps:get(<<"k2">>, M1),
+
+    %% error cases
+    do_badmap(fun(T) ->
+		      {'EXIT',{{badmap,T},[{maps,get,_,_}|_]}} =
+			  (catch maps:get(a, T))
+	      end),
+
+    {'EXIT',{{badkey,{1,1}},[{maps,get,_,_}|_]}} =
+	(catch maps:get({1,1}, #{{1,1.0} => "tuple"})),
+    {'EXIT',{{badkey,a},[{maps,get,_,_}|_]}} = (catch maps:get(a, #{})),
+    {'EXIT',{{badkey,a},[{maps,get,_,_}|_]}} =
+	(catch maps:get(a, #{b=>1, c=>2})),
+    ok.
+
+t_bif_map_find(Config) when is_list(Config) ->
+    %% small map
+    {ok, 1}     = maps:find(a, #{ a=> 1}),
+    {ok, 2}     = maps:find(b, #{ a=> 1, b => 2}),
+    {ok, "int"} = maps:find(1, #{ 1   => "int"}),
+    {ok, "float"} = maps:find(1.0, #{ 1.0=> "float"}),
+
+    {ok, "hi"} = maps:find("hello", #{ a=>1, "hello" => "hi"}),
+    {ok, "tuple hi"} = maps:find({1,1.0}, #{ a=>a, {1,1.0} => "tuple hi"}),
+
+    M0 = #{ k1=>"v1", <<"k2">> => <<"v3">> },
+    {ok, "v4"} = maps:find(<<"k2">>, M0#{ <<"k2">> => "v4" }),
+
+    %% large map
+    M1   = maps:from_list([{I,I}||I<-lists:seq(1,100)] ++
+			  [{a,1},{b,2},{"hello","hi"},{{1,1.0},"tuple hi"},
+			   {k1,"v1"},{<<"k2">>,"v3"}]),
+    {ok, 1}    = maps:find(a, M1),
+    {ok, 2}    = maps:find(b, M1),
+    {ok, "hi"} = maps:find("hello", M1),
+    {ok, "tuple hi"} = maps:find({1,1.0}, M1),
+    {ok, "v3"} = maps:find(<<"k2">>, M1),
+
+    %% error case
+    error = maps:find(a,#{}),
+    error = maps:find(a,#{b=>1, c=>2}),
+    error = maps:find(1.0, #{ 1 => "int"}),
+    error = maps:find(1, #{ 1.0  => "float"}),
+    error = maps:find({1.0,1}, #{ a=>a, {1,1.0} => "tuple hi"}), % reverse types in tuple key
+
+    do_badmap(fun(T) ->
+		      {'EXIT',{{badmap,T},[{maps,find,_,_}|_]}} =
+			  (catch maps:find(a, T))
+	      end),
+    ok.
+
+
+t_bif_map_is_key(Config) when is_list(Config) ->
+    M1 = #{ "hi" => "hello", int => 3, <<"key">> => <<"value">>, 4 => number},
+
+    true  = maps:is_key("hi", M1),
+    true  = maps:is_key(int, M1),
+    true  = maps:is_key(<<"key">>, M1),
+    true  = maps:is_key(4, M1),
+
+    false = maps:is_key(5, M1),
+    false = maps:is_key(<<"key2">>, M1),
+    false = maps:is_key("h", M1),
+    false = maps:is_key("hello", M1),
+    false = maps:is_key(atom, M1),
+    false = maps:is_key(any, #{}),
+
+    false = maps:is_key("hi", maps:remove("hi", M1)),
+    true  = maps:is_key("hi", M1),
+    true  = maps:is_key(1, maps:put(1, "number", M1)),
+    false = maps:is_key(1.0, maps:put(1, "number", M1)),
+
+    %% error case
+    do_badmap(fun(T) ->
+		      {'EXIT',{{badmap,T},[{maps,is_key,_,_}|_]}} =
+			  (catch maps:is_key(a, T))
+	      end),
+    ok.
+
+t_bif_map_keys(Config) when is_list(Config) ->
+    [] = maps:keys(#{}),
+
+    [1,2,3,4,5] = lists:sort(maps:keys(#{ 1 => a, 2 => b, 3 => c, 4 => d, 5 => e})),
+    [1,2,3,4,5] = lists:sort(maps:keys(#{ 4 => d, 5 => e, 1 => a, 2 => b, 3 => c})),
+
+    % values in key order: [4,int,"hi",<<"key">>]
+    M1 = #{ "hi" => "hello", int => 3, <<"key">> => <<"value">>, 4 => number},
+    [4,int,"hi",<<"key">>] = lists:sort(maps:keys(M1)),
+
+    %% error case
+    do_badmap(fun(T) ->
+		      {'EXIT',{{badmap,T},[{maps,keys,_,_}|_]}} =
+			  (catch maps:keys(T))
+	      end),
+    ok.
+
+t_bif_map_new(Config) when is_list(Config) ->
+    #{} = maps:new(),
+    0   = erlang:map_size(maps:new()),
+    ok.
+
+t_bif_map_merge(Config) when is_list(Config) ->
+    0   = erlang:map_size(maps:merge(#{},#{})),
+
+    M0 = #{ "hi" => "hello", int => 3, <<"key">> => <<"value">>,
+	4 => number, 18446744073709551629 => wat},
+
+    #{ "hi" := "hello", int := 3, <<"key">> := <<"value">>,
+	4 := number, 18446744073709551629 := wat} = maps:merge(#{}, M0),
+
+    #{ "hi" := "hello", int := 3, <<"key">> := <<"value">>,
+	4 := number, 18446744073709551629 := wat} = maps:merge(M0, #{}),
+
+    M1 = #{ "hi" => "hello again", float => 3.3, {1,2} => "tuple", 4 => integer },
+
+    #{4 := number, 18446744073709551629 := wat, float := 3.3, int := 3,
+	{1,2} := "tuple", "hi" := "hello", <<"key">> := <<"value">>} = maps:merge(M1,M0),
+
+    #{4 := integer, 18446744073709551629 := wat, float := 3.3, int := 3,
+	{1,2} := "tuple", "hi" := "hello again", <<"key">> := <<"value">>} = maps:merge(M0,M1),
+
+    %% try deep collisions
+    N  = 150000,
+    Is = lists:seq(1,N),
+    M2 = maps:from_list([{I,I}||I<-Is]),
+    150000 = maps:size(M2),
+    M3 = maps:from_list([{<<I:32>>,I}||I<-Is]),
+    150000 = maps:size(M3),
+    M4 = maps:merge(M2,M3),
+    300000 = maps:size(M4),
+    M5 = maps:from_list([{integer_to_list(I),I}||I<-Is]),
+    150000 = maps:size(M5),
+    M6 = maps:merge(M4,M5),
+    450000 = maps:size(M6),
+    M7 = maps:from_list([{float(I),I}||I<-Is]),
+    150000 = maps:size(M7),
+    M8 = maps:merge(M7,M6),
+    600000 = maps:size(M8),
+
+    #{      1 := 1,           "1" := 1,           <<1:32>> := 1      } = M8,
+    #{     10 := 10,         "10" := 10,         <<10:32>> := 10     } = M8,
+    #{    100 := 100,       "100" := 100,       <<100:32>> := 100    } = M8,
+    #{   1000 := 1000,     "1000" := 1000,     <<1000:32>> := 1000   } = M8,
+    #{  10000 := 10000,   "10000" := 10000,   <<10000:32>> := 10000  } = M8,
+    #{ 100000 := 100000, "100000" := 100000, <<100000:32>> := 100000 } = M8,
+
+    %% overlapping
+    M8 = maps:merge(M2,M8),
+    M8 = maps:merge(M3,M8),
+    M8 = maps:merge(M4,M8),
+    M8 = maps:merge(M5,M8),
+    M8 = maps:merge(M6,M8),
+    M8 = maps:merge(M7,M8),
+    M8 = maps:merge(M8,M8),
+
+    %% maps:merge/2 and mixed
+
+    Ks1 = [764492191,2361333849], %% deep collision
+    Ks2 = lists:seq(1,33),
+    M9  = maps:from_list([{K,K}||K <- Ks1]),
+    M10 = maps:from_list([{K,K}||K <- Ks2]),
+    M11 = maps:merge(M9,M10),
+    ok = check_keys_exist(Ks1 ++ Ks2, M11),
+
+    %% error case
+    do_badmap(fun(T) ->
+		      {'EXIT',{{badmap,T},[{maps,merge,_,_}|_]}} =
+			  (catch maps:merge(#{}, T)),
+		      {'EXIT',{{badmap,T},[{maps,merge,_,_}|_]}} =
+			  (catch maps:merge(T, #{})),
+		      {'EXIT',{{badmap,T},[{maps,merge,_,_}|_]}} =
+			  (catch maps:merge(T, T))
+	      end),
+    ok.
+
+
+t_bif_map_put(Config) when is_list(Config) ->
+    M0 = #{ "hi" => "hello", int => 3, <<"key">> => <<"value">>,
+	4 => number, 18446744073709551629 => wat},
+
+    M1 = #{ "hi" := "hello"} = maps:put("hi", "hello", #{}),
+
+    true = is_members(["hi"],maps:keys(M1)),
+    true = is_members(["hello"],maps:values(M1)),
+
+    M2 = #{ int := 3 } = maps:put(int, 3, M1),
+
+    true = is_members([int,"hi"],maps:keys(M2)),
+    true = is_members([3,"hello"],maps:values(M2)),
+
+    M3 = #{ <<"key">> := <<"value">> } = maps:put(<<"key">>, <<"value">>, M2),
+
+    true = is_members([int,"hi",<<"key">>],maps:keys(M3)),
+    true = is_members([3,"hello",<<"value">>],maps:values(M3)),
+
+    M4 = #{ 18446744073709551629 := wat } = maps:put(18446744073709551629, wat, M3),
+
+    true = is_members([18446744073709551629,int,"hi",<<"key">>],maps:keys(M4)),
+    true = is_members([wat,3,"hello",<<"value">>],maps:values(M4)),
+
+    M0 = #{ 4 := number } = M5 = maps:put(4, number, M4),
+
+    true = is_members([4,18446744073709551629,int,"hi",<<"key">>],maps:keys(M5)),
+    true = is_members([number,wat,3,"hello",<<"value">>],maps:values(M5)),
+
+    M6 = #{ <<"key">> := <<"other value">> } = maps:put(<<"key">>, <<"other value">>, M5),
+
+    true = is_members([4,18446744073709551629,int,"hi",<<"key">>],maps:keys(M6)),
+    true = is_members([number,wat,3,"hello",<<"other value">>],maps:values(M6)),
+
+    %% error case
+    do_badmap(fun(T) ->
+		      {'EXIT',{{badmap,T},[{maps,put,_,_}|_]}} =
+			  (catch maps:put(1, a, T))
+	      end),
+    ok.
+
+is_members(Ks,Ls) when length(Ks) =/= length(Ls) -> false;
+is_members(Ks,Ls) -> is_members_do(Ks,Ls).
+
+is_members_do([],[]) -> true;
+is_members_do([],_) -> false;
+is_members_do([K|Ks],Ls) ->
+    is_members_do(Ks, lists:delete(K,Ls)).
+
+t_bif_map_remove(Config) when is_list(Config) ->
+    0  = erlang:map_size(maps:remove(some_key, #{})),
+
+    M0 = #{ "hi" => "hello", int => 3, <<"key">> => <<"value">>,
+	4 => number, 18446744073709551629 => wat},
+
+    M1 = maps:remove("hi", M0),
+    true = is_members([4,18446744073709551629,int,<<"key">>],maps:keys(M1)),
+    true = is_members([number,wat,3,<<"value">>],maps:values(M1)),
+
+    M2 = maps:remove(int, M1),
+    true = is_members([4,18446744073709551629,<<"key">>],maps:keys(M2)),
+    true = is_members([number,wat,<<"value">>],maps:values(M2)),
+
+    M3 = maps:remove(<<"key">>, M2),
+    true = is_members([4,18446744073709551629],maps:keys(M3)),
+    true = is_members([number,wat],maps:values(M3)),
+
+    M4 = maps:remove(18446744073709551629, M3),
+    true = is_members([4],maps:keys(M4)),
+    true = is_members([number],maps:values(M4)),
+
+    M5 = maps:remove(4, M4),
+    [] = maps:keys(M5),
+    [] = maps:values(M5),
+
+    M0 = maps:remove(5,M0),
+    M0 = maps:remove("hi there",M0),
+
+    #{ "hi" := "hello", int := 3, 4 := number} = maps:remove(18446744073709551629,maps:remove(<<"key">>,M0)),
+
+    %% error case
+    do_badmap(fun(T) ->
+		      {'EXIT',{{badmap,T},[{maps,remove,_,_}|_]}} =
+	(catch maps:remove(a, T))
+	      end),
+     ok.
+
+t_bif_map_update(Config) when is_list(Config) ->
+    M0 = #{ "hi" => "hello", int => 3, <<"key">> => <<"value">>,
+	4 => number, 18446744073709551629 => wat},
+
+    #{ "hi" := "hello again", int := 3, <<"key">> := <<"value">>,
+	4 := number, 18446744073709551629 := wat} = maps:update("hi", "hello again", M0),
+
+    #{ "hi" := "hello", int := 1337, <<"key">> := <<"value">>,
+	4 := number, 18446744073709551629 := wat} = maps:update(int, 1337, M0),
+
+    #{ "hi" := "hello", int := 3, <<"key">> := <<"new value">>,
+	4 := number, 18446744073709551629 := wat} = maps:update(<<"key">>, <<"new value">>, M0),
+
+    #{ "hi" := "hello", int := 3, <<"key">> := <<"value">>,
+	4 := integer, 18446744073709551629 := wat} = maps:update(4, integer, M0),
+
+    #{ "hi" := "hello", int := 3, <<"key">> := <<"value">>,
+	4 := number, 18446744073709551629 := wazzup} = maps:update(18446744073709551629, wazzup, M0),
+
+    %% error case
+    do_badmap(fun(T) ->
+		      {'EXIT',{{badmap,T},[{maps,update,_,_}|_]}} =
+			  (catch maps:update(1, none, T))
+	      end),
+    ok.
+
+
+
+t_bif_map_values(Config) when is_list(Config) ->
+
+    [] = maps:values(#{}),
+    [1] = maps:values(#{a=>1}),
+
+    true = is_members([a,b,c,d,e],maps:values(#{ 1 => a, 2 => b, 3 => c, 4 => d, 5 => e})),
+    true = is_members([a,b,c,d,e],maps:values(#{ 4 => d, 5 => e, 1 => a, 2 => b, 3 => c})),
+
+    M1 = #{ "hi" => "hello", int => 3, <<"key">> => <<"value">>, 4 => number},
+    M2 = M1#{ "hi" => "hello2", <<"key">> => <<"value2">> },
+    true = is_members([number,3,"hello2",<<"value2">>],maps:values(M2)),
+    true = is_members([number,3,"hello",<<"value">>],maps:values(M1)),
+
+    Vs = lists:seq(1000,20000),
+    M3 = maps:from_list([{K,K}||K<-Vs]),
+    M4 = maps:merge(M1,M3),
+    M5 = maps:merge(M2,M3),
+    true = is_members(Vs,maps:values(M3)),
+    true = is_members([number,3,"hello",<<"value">>]++Vs,maps:values(M4)),
+    true = is_members([number,3,"hello2",<<"value2">>]++Vs,maps:values(M5)),
+
+    %% error case
+    do_badmap(fun(T) ->
+		      {'EXIT',{{badmap,T},[{maps,values,_,_}|_]}} =
+			  (catch maps:values(T))
+	      end),
+    ok.
+
+t_erlang_hash(Config) when is_list(Config) ->
+
+    ok = t_bif_erlang_phash2(),
+    ok = t_bif_erlang_phash(),
+    ok = t_bif_erlang_hash(),
+
+    ok.
+
+t_bif_erlang_phash2() ->
+
+    39679005 = erlang:phash2(#{}),
+    33667975 = erlang:phash2(#{ a => 1, "a" => 2, <<"a">> => 3, {a,b} => 4 }), % 78942764
+    95332690 = erlang:phash2(#{ 1 => a, 2 => "a", 3 => <<"a">>, 4 => {a,b} }), % 37338230
+    108954384 = erlang:phash2(#{ 1 => a }), % 14363616
+    59617982 = erlang:phash2(#{ a => 1 }), % 51612236
+
+    42770201 = erlang:phash2(#{{} => <<>>}), % 37468437
+    71687700 = erlang:phash2(#{<<>> => {}}), % 44049159
+
+    M0 = #{ a => 1, "key" => <<"value">> },
+    M1 = maps:remove("key",M0),
+    M2 = M1#{ "key" => <<"value">> },
+
+    70249457 = erlang:phash2(M0), % 118679416
+    59617982 = erlang:phash2(M1), % 51612236
+    70249457 = erlang:phash2(M2), % 118679416
+    ok.
+
+t_bif_erlang_phash() ->
+    Sz = 1 bsl 32,
+    1113425985 = erlang:phash(#{},Sz), % 268440612
+    1510068139 = erlang:phash(#{ a => 1, "a" => 2, <<"a">> => 3, {a,b} => 4 },Sz), % 1196461908
+    3182345590 = erlang:phash(#{ 1 => a, 2 => "a", 3 => <<"a">>, 4 => {a,b} },Sz), % 3944426064
+    2927531828 = erlang:phash(#{ 1 => a },Sz), % 1394238263
+    1670235874 = erlang:phash(#{ a => 1 },Sz), % 4066388227
+
+    3935089469 = erlang:phash(#{{} => <<>>},Sz), % 1578050717
+    71692856   = erlang:phash(#{<<>> => {}},Sz), % 1578050717
+
+    M0 = #{ a => 1, "key" => <<"value">> },
+    M1 = maps:remove("key",M0),
+    M2 = M1#{ "key" => <<"value">> },
+
+    2620391445 = erlang:phash(M0,Sz), % 3590546636
+    1670235874 = erlang:phash(M1,Sz), % 4066388227
+    2620391445 = erlang:phash(M2,Sz), % 3590546636
+    ok.
+
+t_bif_erlang_hash() ->
+    Sz = 1 bsl 27 - 1,
+    39684169 = erlang:hash(#{},Sz),  % 5158
+    33673142 = erlang:hash(#{ a => 1, "a" => 2, <<"a">> => 3, {a,b} => 4 },Sz), % 71555838
+    95337869 = erlang:hash(#{ 1 => a, 2 => "a", 3 => <<"a">>, 4 => {a,b} },Sz), % 5497225
+    108959561 = erlang:hash(#{ 1 => a },Sz), % 126071654
+    59623150 = erlang:hash(#{ a => 1 },Sz), % 126426236
+
+    42775386 = erlang:hash(#{{} => <<>>},Sz), % 101655720
+    71692856 = erlang:hash(#{<<>> => {}},Sz), % 101655720
+
+    M0 = #{ a => 1, "key" => <<"value">> },
+    M1 = maps:remove("key",M0),
+    M2 = M1#{ "key" => <<"value">> },
+
+    70254632 = erlang:hash(M0,Sz), % 38260486
+    59623150 = erlang:hash(M1,Sz), % 126426236
+    70254632 = erlang:hash(M2,Sz), % 38260486
+    ok.
+
+
+t_map_encode_decode(Config) when is_list(Config) ->
+    <<131,116,0,0,0,0>> = erlang:term_to_binary(#{}),
+    Pairs = [
+	{a,b},{"key","values"},{<<"key">>,<<"value">>},
+	{1,b},{[atom,1],{<<"wat">>,1,2,3}},
+	{aa,"values"},
+	{1 bsl 64 + (1 bsl 50 - 1), sc1},
+	{99, sc2},
+	{1 bsl 65 + (1 bsl 51 - 1), sc3},
+	{88, sc4},
+	{1 bsl 66 + (1 bsl 52 - 1), sc5},
+	{77, sc6},
+	{1 bsl 67 + (1 bsl 53 - 1), sc3},
+	{75, sc6}, {-10,sc8},
+	{<<>>, sc9}, {3.14158, sc10},
+	{[3.14158], sc11}, {more_atoms, sc12},
+	{{more_tuples}, sc13}, {self(), sc14},
+	{{},{}},{[],[]}
+    ],
+    ok = map_encode_decode_and_match(Pairs,[],#{}),
+
+    %% check sorting
+
+    %% literally #{ b=>2, a=>1 } in the internal order
+    #{ a:=1, b:=2 } =
+	erlang:binary_to_term(<<131,116,0,0,0,2,100,0,1,98,97,2,100,0,1,97,97,1>>),
+
+
+    %% literally #{ "hi" => "value", a=>33, b=>55 } in the internal order
+    #{ a:=33, b:=55, "hi" := "value"} = erlang:binary_to_term(<<131,116,0,0,0,3,
+	107,0,2,104,105,            % "hi" :: list()
+	107,0,5,118,97,108,117,101, % "value" :: list()
+	100,0,1,97,                 % a :: atom()
+	97,33,                      % 33 :: integer()
+	100,0,1,98,                 % b :: atom()
+	97,55                       % 55 :: integer()
+	>>),
+
+    %% Maps of different sizes
+    lists:foldl(fun(Key, M0) ->
+			M1 = M0#{Key => Key},
+			case Key rem 17 of
+			    0 ->
+				M1 = binary_to_term(term_to_binary(M1));
+			    _ ->
+				ok
+			end,
+			M1
+		end,
+		#{},
+		lists:seq(1,10000)),
+
+    %% many maps in same binary
+    MapList = lists:foldl(fun(K, [M|_]=Acc) -> [M#{K => K} | Acc] end,
+			  [#{}],
+			  lists:seq(1,100)),
+    MapList = binary_to_term(term_to_binary(MapList)),
+    MapListR = lists:reverse(MapList),
+    MapListR = binary_to_term(term_to_binary(MapListR)),
+
+    %% error cases
+    %% template: <<131,116,0,0,0,2,100,0,1,97,100,0,1,98,97,1,97,1>>
+    %% which is: #{ a=>1, b=>1 }
+
+    %% uniqueness violation
+    %% literally #{ a=>1, "hi"=>"value", a=>2 }
+    {'EXIT',{badarg,[{_,_,_,_}|_]}} = (catch
+	erlang:binary_to_term(<<131,116,0,0,0,3,
+			       100,0,1,97,
+			       97,1,
+			       107,0,2,104,105,
+			       107,0,5,118,97,108,117,101,
+			       100,0,1,97,
+			       97,2>>)),
+
+    %% bad size (too large)
+    {'EXIT',{badarg,[{_,_,_,_}|_]}} = (catch
+	erlang:binary_to_term(<<131,116,0,0,0,12,100,0,1,97,97,1,100,0,1,98,97,1>>)),
+
+    %% bad size (too small) .. should fail just truncate it .. weird.
+    %% possibly change external format so truncated will be #{a:=1}
+    #{ a:=b } =
+	erlang:binary_to_term(<<131,116,0,0,0,1,100,0,1,97,100,0,1,98,97,1,97,1>>),
+
+    ok.
+
+map_encode_decode_and_match([{K,V}|Pairs], EncodedPairs, M0) ->
+    M1 = maps:put(K,V,M0),
+    B0 = erlang:term_to_binary(M1),
+    Ls = [{erlang:term_to_binary(K), erlang:term_to_binary(V)}|EncodedPairs],
+    ok = match_encoded_map(B0, length(Ls), Ls),
+    %% decode and match it
+    M1 = erlang:binary_to_term(B0),
+    map_encode_decode_and_match(Pairs,Ls,M1);
+map_encode_decode_and_match([],_,_) -> ok.
+
+match_encoded_map(<<131,116,Size:32,Encoded/binary>>,Size,Items) ->
+    match_encoded_map_stripped_size(Encoded,Items,Items);
+match_encoded_map(_,_,_) -> no_match_size.
+
+match_encoded_map_stripped_size(<<>>,_,_) -> ok;
+match_encoded_map_stripped_size(B0,[{<<131,K/binary>>,<<131,V/binary>>}|Items],Ls) ->
+    Ksz = byte_size(K),
+    Vsz = byte_size(V),
+    case B0 of
+	<<K:Ksz/binary,V:Vsz/binary,B1/binary>> ->
+	    match_encoded_map_stripped_size(B1,Ls,Ls);
+	_ ->
+	    match_encoded_map_stripped_size(B0,Items,Ls)
+    end;
+match_encoded_map_stripped_size(_,[],_) -> fail.
+
+
+t_bif_map_to_list(Config) when is_list(Config) ->
+    [] = maps:to_list(#{}),
+    [{a,1},{b,2}] = lists:sort(maps:to_list(#{a=>1,b=>2})),
+    [{a,1},{b,2},{c,3}] = lists:sort(maps:to_list(#{c=>3,a=>1,b=>2})),
+    [{a,1},{b,2},{g,3}] = lists:sort(maps:to_list(#{g=>3,a=>1,b=>2})),
+    [{a,1},{b,2},{g,3},{"c",4}] = lists:sort(maps:to_list(#{g=>3,a=>1,b=>2,"c"=>4})),
+    [{3,v2},{hi,v4},{{hi,3},v5},{"hi",v3},{<<"hi">>,v1}] =
+	lists:sort(maps:to_list(#{<<"hi">>=>v1,3=>v2,"hi"=>v3,hi=>v4,{hi,3}=>v5})),
+
+    [{3,v7},{hi,v9},{{hi,3},v10},{"hi",v8},{<<"hi">>,v6}] =
+	lists:sort(maps:to_list(#{<<"hi">>=>v1,3=>v2,"hi"=>v3,hi=>v4,{hi,3}=>v5,
+				  <<"hi">>=>v6,3=>v7,"hi"=>v8,hi=>v9,{hi,3}=>v10})),
+
+    %% error cases
+    do_badmap(fun(T) ->
+		      {'EXIT', {{badmap,T},_}} =
+			  (catch maps:to_list(T))
+	      end),
+    ok.
+
+
+t_bif_map_from_list(Config) when is_list(Config) ->
+    #{} = maps:from_list([]),
+    A   = maps:from_list([]),
+    0   = erlang:map_size(A),
+
+    #{a:=1,b:=2}      = maps:from_list([{a,1},{b,2}]),
+    #{c:=3,a:=1,b:=2} = maps:from_list([{a,1},{b,2},{c,3}]),
+    #{g:=3,a:=1,b:=2} = maps:from_list([{a,1},{b,2},{g,3}]),
+
+    #{a:=2} = maps:from_list([{a,1},{a,3},{a,2}]),
+
+    #{ <<"hi">>:=v1,3:=v3,"hi":=v6,hi:=v4,{hi,3}:=v5} =
+	maps:from_list([{3,v3},{"hi",v6},{hi,v4},{{hi,3},v5},{<<"hi">>,v1}]),
+
+    #{<<"hi">>:=v6,3:=v8,"hi":=v11,hi:=v9,{hi,3}:=v10} =
+	maps:from_list([ {{hi,3},v3}, {"hi",v0},{3,v1}, {<<"hi">>,v4}, {hi,v2},
+	    {<<"hi">>,v6}, {{hi,3},v10},{"hi",v11}, {hi,v9}, {3,v8}]),
+
+    %% repeated keys (large -> small)
+    Ps1 = [{a,I}|| I <- lists:seq(1,32)],
+    Ps2 = [{a,I}|| I <- lists:seq(33,64)],
+
+    M = maps:from_list(Ps1 ++ [{b,1},{c,1}] ++ Ps2),
+    #{ a := 64, b := 1, c := 1 } = M,
+
+    %% error cases
+    {'EXIT', {badarg,_}} = (catch maps:from_list([{a,b},b])),
+    {'EXIT', {badarg,_}} = (catch maps:from_list([{a,b},{b,b,3}])),
+    {'EXIT', {badarg,_}} = (catch maps:from_list([{a,b},<<>>])),
+    {'EXIT', {badarg,_}} = (catch maps:from_list([{a,b}|{b,a}])),
+    {'EXIT', {badarg,_}} = (catch maps:from_list(a)),
+    {'EXIT', {badarg,_}} = (catch maps:from_list(42)),
+    ok.
+
+t_bif_build_and_check(Config) when is_list(Config) ->
+    ok = check_build_and_remove(750,[
+				      fun(K) -> [K,K] end,
+				      fun(K) -> [float(K),K] end,
+				      fun(K) -> K end,
+				      fun(K) -> {1,K} end,
+				      fun(K) -> {K} end,
+				      fun(K) -> [K|K] end,
+				      fun(K) -> [K,1,2,3,4] end,
+				      fun(K) -> {K,atom} end,
+				      fun(K) -> float(K) end,
+				      fun(K) -> integer_to_list(K) end,
+				      fun(K) -> list_to_atom(integer_to_list(K)) end,
+				      fun(K) -> [K,{K,[K,{K,[K]}]}] end,
+				      fun(K) -> <<K:32>> end
+			      ]),
+
+    ok.
+
+check_build_and_remove(_,[]) -> ok;
+check_build_and_remove(N,[F|Fs]) ->
+    {M,Ks} = build_and_check(N, maps:new(), F, []),
+    ok     = remove_and_check(Ks,M),
+    check_build_and_remove(N,Fs).
+
+build_and_check(0, M0, _, Ks) -> {M0, Ks};
+build_and_check(N, M0, F, Ks) ->
+    K  = build_key(F,N),
+    M1 = maps:put(K,K,M0),
+    ok = check_keys_exist([I||{I,_} <- [{K,M1}|Ks]], M1),
+    M2 = maps:update(K,v,M1),
+    v  = maps:get(K,M2),
+    build_and_check(N-1,M1,F,[{K,M1}|Ks]).
+
+remove_and_check([],_) -> ok;
+remove_and_check([{K,Mc}|Ks], M0) ->
+    K     = maps:get(K,M0),
+    true  = maps:is_key(K,M0),
+    true  = Mc =:= M0,
+    true  = M0 == Mc,
+    M1    = maps:remove(K,M0),
+    false = M1 =:= Mc,
+    false = Mc == M1,
+    false = maps:is_key(K,M1),
+    true  = maps:is_key(K,M0),
+    ok    = check_keys_exist([I||{I,_} <- Ks],M1),
+    error = maps:find(K,M1),
+    remove_and_check(Ks, M1).
+
+build_key(F,N) when N rem 3 =:= 0 -> F(N);
+build_key(F,N) when N rem 3 =:= 1 -> K = F(N), {K,K};
+build_key(F,N) when N rem 3 =:= 2 -> K = F(N), [K,K].
+
+check_keys_exist([], _) -> ok;
+check_keys_exist([K|Ks],M) ->
+    true = maps:is_key(K,M),
+    check_keys_exist(Ks,M).
+
+t_bif_merge_and_check(Config) when is_list(Config) ->
+
+    io:format("rand:export_seed() -> ~p\n",[rand:export_seed()]),
+
+    %% simple disjunct ones
+    %% make sure all keys are unique
+    Kss = [[a,b,c,d],
+	   [1,2,3,4],
+	   [],
+	   ["hi"],
+	   [e],
+	   [build_key(fun(K) -> {small,K} end, I) || I <- lists:seq(1,32)],
+	   lists:seq(5, 28),
+	   lists:seq(29, 59),
+	   [build_key(fun(K) -> integer_to_list(K) end, I) || I <- lists:seq(2000,10000)],
+	   [build_key(fun(K) -> <<K:32>> end, I) || I <- lists:seq(1,80)],
+	   [build_key(fun(K) -> {<<K:32>>} end, I) || I <- lists:seq(100,1000)]],
+
+
+    KsMs = build_keys_map_pairs(Kss),
+    Cs   = [{CKs1,CM1,CKs2,CM2} || {CKs1,CM1} <- KsMs, {CKs2,CM2} <- KsMs],
+    ok   = merge_and_check_combo(Cs),
+
+    %% overlapping ones
+
+    KVs1 = [{a,1},{b,2},{c,3}],
+    KVs2 = [{b,3},{c,4},{d,5}],
+    KVs  = [{I,I} || I <- lists:seq(1,32)],
+    KVs3 = KVs1 ++ KVs,
+    KVs4 = KVs2 ++ KVs,
+
+    M1  = maps:from_list(KVs1),
+    M2  = maps:from_list(KVs2),
+    M3  = maps:from_list(KVs3),
+    M4  = maps:from_list(KVs4),
+
+    M12 = maps:merge(M1,M2),
+    ok  = check_key_values(KVs2 ++ [{a,1}], M12),
+    M21 = maps:merge(M2,M1),
+    ok  = check_key_values(KVs1 ++ [{d,5}], M21),
+
+    M34 = maps:merge(M3,M4),
+    ok  = check_key_values(KVs4 ++ [{a,1}], M34),
+    M43 = maps:merge(M4,M3),
+    ok  = check_key_values(KVs3 ++ [{d,5}], M43),
+
+    M14 = maps:merge(M1,M4),
+    ok  = check_key_values(KVs4 ++ [{a,1}], M14),
+    M41 = maps:merge(M4,M1),
+    ok  = check_key_values(KVs1 ++ [{d,5}] ++ KVs, M41),
+
+    [begin Ma = random_map(SzA, a),
+	   Mb = random_map(SzB, b),
+	   ok = merge_maps(Ma, Mb)
+     end || SzA <- [3,10,20,100,200,1000], SzB <- [3,10,20,100,200,1000]],
+
+    ok.
+
+% Generate random map with an average of Sz number of pairs: K -> {V,K}
+random_map(Sz, V) ->
+    random_map_insert(#{}, 0, V, Sz*2).
+
+random_map_insert(M0, K0, _, Sz) when K0 > Sz ->
+    M0;
+random_map_insert(M0, K0, V, Sz) ->
+    Key = K0 + rand:uniform(3),
+    random_map_insert(M0#{Key => {V,Key}}, Key, V, Sz).
+
+
+merge_maps(A, B) ->
+    AB = maps:merge(A, B),
+    %%io:format("A=~p\nB=~p\n",[A,B]),
+    maps_foreach(fun(K,VB) -> VB = maps:get(K, AB)
+		 end, B),
+    maps_foreach(fun(K,VA) ->
+			 case {maps:get(K, AB),maps:find(K, B)} of
+			     {VA, error} -> ok;
+			     {VB, {ok, VB}} -> ok
+			 end
+		 end, A),
+
+    maps_foreach(fun(K,V) ->
+			 case {maps:find(K, A),maps:find(K, B)} of
+			     {{ok, V}, error} -> ok;
+			     {error, {ok, V}} -> ok;
+			     {{ok,_}, {ok, V}} -> ok
+			 end
+		 end, AB),
+    ok.
+
+maps_foreach(Fun, Map) ->
+    maps:fold(fun(K,V,_) -> Fun(K,V) end, void, Map).
+
+
+check_key_values([],_) -> ok;
+check_key_values([{K,V}|KVs],M) ->
+    V = maps:get(K,M),
+    check_key_values(KVs,M).
+
+merge_and_check_combo([]) -> ok;
+merge_and_check_combo([{Ks1,M1,Ks2,M2}|Cs]) ->
+    M12 = maps:merge(M1,M2),
+    ok  = check_keys_exist(Ks1 ++ Ks2, M12),
+    M21 = maps:merge(M2,M1),
+    ok  = check_keys_exist(Ks1 ++ Ks2, M21),
+
+    true = M12 =:= M21,
+    M12  = M21,
+
+    merge_and_check_combo(Cs).
+
+build_keys_map_pairs([]) -> [];
+build_keys_map_pairs([Ks|Kss]) ->
+    M  = maps:from_list(keys_to_pairs(Ks)),
+    ok = check_keys_exist(Ks, M),
+    [{Ks,M}|build_keys_map_pairs(Kss)].
+
+keys_to_pairs(Ks) -> [{K,K} || K <- Ks].
+
+
+%% Maps module, not BIFs
+t_maps_fold(_Config) ->
+    Vs = lists:seq(1,100),
+    M  = maps:from_list([{{k,I},{v,I}}||I<-Vs]),
+
+    %% fold
+    5050 = maps:fold(fun({k,_},{v,V},A) -> V + A end, 0, M),
+
+    ok.
+
+t_maps_map(_Config) ->
+    Vs = lists:seq(1,100),
+    M1 = maps:from_list([{I,I}||I<-Vs]),
+    M2 = maps:from_list([{I,{token,I}}||I<-Vs]),
+
+    M2 = maps:map(fun(_K,V) -> {token,V} end, M1),
+    ok.
+
+t_maps_size(_Config) ->
+    Vs = lists:seq(1,100),
+    lists:foldl(fun(I,M) ->
+		M1 = maps:put(I,I,M),
+		I  = maps:size(M1),
+		M1
+	end, #{}, Vs),
+    ok.
+
+
+t_maps_without(_Config) ->
+    Ki = [11,22,33,44,55,66,77,88,99],
+    M0 = maps:from_list([{{k,I},{v,I}}||I<-lists:seq(1,100)]),
+    M1 = maps:from_list([{{k,I},{v,I}}||I<-lists:seq(1,100) -- Ki]),
+    M1 = maps:without([{k,I}||I <- Ki],M0),
+    ok.
+
+t_erts_internal_order(_Config) when is_list(_Config) ->
+    M = #{0 => 0,2147483648 => 0},
+    true = M =:= binary_to_term(term_to_binary(M)),
+
+    F1 = fun(_, _) -> 0 end,
+    F2 = fun(_, _) -> 1 end,
+    M0 = maps:from_list( [{-2147483649, 0}, {0,0}, {97, 0}, {false, 0}, {flower, 0}, {F1, 0}, {F2, 0}, {<<>>, 0}]),
+    M1 = maps:merge(M0, #{0 => 1}),
+    8  = maps:size(M1),
+    1  = maps:get(0,M1),
+    ok.
+
+t_erts_internal_hash(_Config) when is_list(_Config) ->
+    K1 = 0.0,
+    K2 = 0.0/-1,
+    M  = maps:from_list([{I,I}||I<-lists:seq(1,32)]),
+
+    M1 = M#{ K1 => a, K2 => b },
+    b  = maps:get(K2,M1),
+
+    M2 = M#{ K2 => a, K1 => b },
+    b  = maps:get(K1,M2),
+
+    %% test previously faulty hash list optimization
+
+    M3 = M#{[0] => a, [0,0] => b, [0,0,0] => c, [0,0,0,0] => d},
+    a  = maps:get([0],M3),
+    b  = maps:get([0,0],M3),
+    c  = maps:get([0,0,0],M3),
+    d  = maps:get([0,0,0,0],M3),
+
+    M4 = M#{{[0]} => a, {[0,0]} => b, {[0,0,0]} => c, {[0,0,0,0]} => d},
+    a  = maps:get({[0]},M4),
+    b  = maps:get({[0,0]},M4),
+    c  = maps:get({[0,0,0]},M4),
+    d  = maps:get({[0,0,0,0]},M4),
+
+    M5 = M3#{[0,0,0] => e, [0,0,0,0] => f, [0,0,0,0,0] => g,
+             [0,0,0,0,0,0] => h, [0,0,0,0,0,0,0] => i,
+             [0,0,0,0,0,0,0,0] => j, [0,0,0,0,0,0,0,0,0] => k},
+
+    a  = maps:get([0],M5),
+    b  = maps:get([0,0],M5),
+    e  = maps:get([0,0,0],M5),
+    f  = maps:get([0,0,0,0],M5),
+    g  = maps:get([0,0,0,0,0],M5),
+    h  = maps:get([0,0,0,0,0,0],M5),
+    i  = maps:get([0,0,0,0,0,0,0],M5),
+    j  = maps:get([0,0,0,0,0,0,0,0],M5),
+    k  = maps:get([0,0,0,0,0,0,0,0,0],M5),
+
+    M6 = M4#{{[0,0,0]} => e, {[0,0,0,0]} => f, {[0,0,0,0,0]} => g,
+             {[0,0,0,0,0,0]} => h, {[0,0,0,0,0,0,0]} => i,
+             {[0,0,0,0,0,0,0,0]} => j, {[0,0,0,0,0,0,0,0,0]} => k},
+
+    a  = maps:get({[0]},M6),
+    b  = maps:get({[0,0]},M6),
+    e  = maps:get({[0,0,0]},M6),
+    f  = maps:get({[0,0,0,0]},M6),
+    g  = maps:get({[0,0,0,0,0]},M6),
+    h  = maps:get({[0,0,0,0,0,0]},M6),
+    i  = maps:get({[0,0,0,0,0,0,0]},M6),
+    j  = maps:get({[0,0,0,0,0,0,0,0]},M6),
+    k  = maps:get({[0,0,0,0,0,0,0,0,0]},M6),
+
+    M7 = maps:merge(M5,M6),
+
+    a  = maps:get([0],M7),
+    b  = maps:get([0,0],M7),
+    e  = maps:get([0,0,0],M7),
+    f  = maps:get([0,0,0,0],M7),
+    g  = maps:get([0,0,0,0,0],M7),
+    h  = maps:get([0,0,0,0,0,0],M7),
+    i  = maps:get([0,0,0,0,0,0,0],M7),
+    j  = maps:get([0,0,0,0,0,0,0,0],M7),
+    k  = maps:get([0,0,0,0,0,0,0,0,0],M7),
+    a  = maps:get({[0]},M7),
+    b  = maps:get({[0,0]},M7),
+    e  = maps:get({[0,0,0]},M7),
+    f  = maps:get({[0,0,0,0]},M7),
+    g  = maps:get({[0,0,0,0,0]},M7),
+    h  = maps:get({[0,0,0,0,0,0]},M7),
+    i  = maps:get({[0,0,0,0,0,0,0]},M7),
+    j  = maps:get({[0,0,0,0,0,0,0,0]},M7),
+    k  = maps:get({[0,0,0,0,0,0,0,0,0]},M7),
+    ok.
+
+t_pdict(_Config) ->
+
+    put(#{ a => b, b => a},#{ c => d}),
+    put(get(#{ a => b, b => a}),1),
+    1 = get(#{ c => d}),
+    #{ c := d } = get(#{ a => b, b => a}).
+
+t_ets(_Config) ->
+
+    Tid = ets:new(map_table,[]),
+
+    [ets:insert(Tid,{maps:from_list([{I,-I}]),I}) || I <- lists:seq(1,100)],
+
+
+    [{#{ 2 := -2},2}] = ets:lookup(Tid,#{ 2 => -2 }),
+
+    %% Test equal
+    [3,4] = lists:sort(
+	      ets:select(Tid,[{{'$1','$2'},
+			       [{'or',{'==','$1',#{ 3 => -3 }},
+				 {'==','$1',#{ 4 => -4 }}}],
+			       ['$2']}])),
+    %% Test match
+    [30,50] = lists:sort(
+		ets:select(Tid,
+			   [{{#{ 30 => -30}, '$1'},[],['$1']},
+			    {{#{ 50 => -50}, '$1'},[],['$1']}]
+			  )),
+
+    ets:insert(Tid,{#{ a => b, b => c, c => a},transitivity}),
+
+    %% Test equal with map of different size
+    [] = ets:select(Tid,[{{'$1','_'},[{'==','$1',#{ b => c }}],['$_']}]),
+
+    %% Test match with map of different size
+    %[{#{ a := b },_}] = ets:select(Tid,[{{#{ b => c },'_'},[],['$_']}]),
+
+    %%% Test match with don't care value
+    %[{#{ a := b },_}] = ets:select(Tid,[{{#{ b => '_' },'_'},[],['$_']}]),
+
+    %% Test is_map bif
+    101 = length(ets:select(Tid,[{'$1',[{is_map,{element,1,'$1'}}],['$1']}])),
+    ets:insert(Tid,{not_a_map,2}),
+    101 = length(ets:select(Tid,[{'$1',[{is_map,{element,1,'$1'}}],['$1']}])),
+    ets:insert(Tid,{{nope,a,tuple},2}),
+    101 = length(ets:select(Tid,[{'$1',[{is_map,{element,1,'$1'}}],['$1']}])),
+
+    %% Test map_size bif
+    [3] = ets:select(Tid,[{{'$1','_'},[{'==',{map_size,'$1'},3}],
+			   [{map_size,'$1'}]}]),
+
+    true = ets:delete(Tid,#{50 => -50}),
+    [] = ets:lookup(Tid,#{50 => -50}),
+
+    ets:delete(Tid),
+    ok.
+
+t_dets(_Config) ->
+    ok.
+
+t_tracing(_Config) ->
+
+    dbg:stop_clear(),
+    {ok,Tracer} = dbg:tracer(process,{fun trace_collector/2, self()}),
+    dbg:p(self(),c),
+
+    %% Test basic map call
+    {ok,_} = dbg:tpl(?MODULE,id,x),
+    #{ a => b },
+    {trace,_,call,{?MODULE,id,[#{ a := b }]}} = getmsg(Tracer),
+    {trace,_,return_from,{?MODULE,id,1},#{ a := b }} = getmsg(Tracer),
+    dbg:ctpl(),
+
+    %% Test equals in argument list
+    {ok,_} = dbg:tpl(?MODULE,id,[{['$1'],[{'==','$1',#{ b => c}}],
+				  [{return_trace}]}]),
+    #{ a => b },
+    #{ b => c },
+    {trace,_,call,{?MODULE,id,[#{ b := c }]}} = getmsg(Tracer),
+    {trace,_,return_from,{?MODULE,id,1},#{ b := c }} = getmsg(Tracer),
+    dbg:ctpl(),
+
+    %% Test match in head
+    {ok,_} = dbg:tpl(?MODULE,id,[{[#{b => c}],[],[]}]),
+    #{ a => b },
+    #{ b => c },
+    {trace,_,call,{?MODULE,id,[#{ b := c }]}} = getmsg(Tracer),
+    dbg:ctpl(),
+
+    % Test map guard bifs
+    {ok,_} = dbg:tpl(?MODULE,id,[{['$1'],[{is_map,{element,1,'$1'}}],[]}]),
+    #{ a => b },
+    {1,2},
+    {#{ a => b},2},
+    {trace,_,call,{?MODULE,id,[{#{ a := b },2}]}} = getmsg(Tracer),
+    dbg:ctpl(),
+
+    {ok,_} = dbg:tpl(?MODULE,id,[{['$1'],[{'==',{map_size,{element,1,'$1'}},2}],[]}]),
+    #{ a => b },
+    {1,2},
+    {#{ a => b},2},
+    {#{ a => b, b => c},atom},
+    {trace,_,call,{?MODULE,id,[{#{ a := b, b := c },atom}]}} = getmsg(Tracer),
+    dbg:ctpl(),
+
+    %MS = dbg:fun2ms(fun([A]) when A == #{ a => b} -> ok end),
+    %dbg:tpl(?MODULE,id,MS),
+    %#{ a => b },
+    %#{ b => c },
+    %{trace,_,call,{?MODULE,id,[#{ a := b }]}} = getmsg(Tracer),
+    %dbg:ctpl(),
+
+    %% Check to extra messages
+    timeout = getmsg(Tracer),
+
+    dbg:stop_clear(),
+    ok.
+
+getmsg(_Tracer) ->
+    receive V -> V after 100 -> timeout end.
+
+trace_collector(Msg,Parent) ->
+    io:format("~p~n",[Msg]),
+    Parent ! Msg,
+    Parent.
+
+t_has_map_fields(Config) when is_list(Config) ->
+    true = has_map_fields_1(#{one=>1}),
+    true = has_map_fields_1(#{one=>1,two=>2}),
+    false = has_map_fields_1(#{two=>2}),
+    false = has_map_fields_1(#{}),
+
+    true = has_map_fields_2(#{c=>1,b=>2,a=>3}),
+    true = has_map_fields_2(#{c=>1,b=>2,a=>3,x=>42}),
+    false = has_map_fields_2(#{b=>2,c=>1}),
+    false = has_map_fields_2(#{x=>y}),
+    false = has_map_fields_2(#{}),
+
+    true = has_map_fields_3(#{c=>1,b=>2,a=>3}),
+    true = has_map_fields_3(#{c=>1,b=>2,a=>3,[]=>42}),
+    true = has_map_fields_3(#{b=>2,a=>3,[]=>42,42.0=>43}),
+    true = has_map_fields_3(#{a=>3,[]=>42,42.0=>43}),
+    true = has_map_fields_3(#{[]=>42,42.0=>43}),
+    false = has_map_fields_3(#{b=>2,c=>1}),
+    false = has_map_fields_3(#{[]=>y}),
+    false = has_map_fields_3(#{42.0=>x,a=>99}),
+    false = has_map_fields_3(#{}),
+
+    ok.
+
+has_map_fields_1(#{one:=_}) -> true;
+has_map_fields_1(#{}) -> false.
+
+has_map_fields_2(#{a:=_,b:=_,c:=_}) -> true;
+has_map_fields_2(#{}) -> false.
+
+has_map_fields_3(#{a:=_,b:=_}) -> true;
+has_map_fields_3(#{[]:=_,42.0:=_}) -> true;
+has_map_fields_3(#{}) -> false.
+
+y_regs(Config) when is_list(Config) ->
+    Val = [length(Config)],
+    Map0 = y_regs_update(#{}, Val),
+    Map2 = y_regs_update(Map0, Val),
+
+    Map3 = maps:from_list([{I,I*I} || I <- lists:seq(1, 100)]),
+    Map4 = y_regs_update(Map3, Val),
+
+    true = is_map(Map2) andalso is_map(Map4),
+
+    ok.
+
+y_regs_update(Map0, Val0) ->
+    Val1 = {t,Val0},
+    K1 = {key,1},
+    K2 = {key,2},
+    Map1 = Map0#{K1=>K1,
+		 a=>Val0,b=>Val0,c=>Val0,d=>Val0,e=>Val0,
+		 f=>Val0,g=>Val0,h=>Val0,i=>Val0,j=>Val0,
+		 k=>Val0,l=>Val0,m=>Val0,n=>Val0,o=>Val0,
+		 p=>Val0,q=>Val0,r=>Val0,s=>Val0,t=>Val0,
+		 u=>Val0,v=>Val0,w=>Val0,x=>Val0,y=>Val0,
+		 z=>Val0,
+		 aa=>Val0,ab=>Val0,ac=>Val0,ad=>Val0,ae=>Val0,
+		 af=>Val0,ag=>Val0,ah=>Val0,ai=>Val0,aj=>Val0,
+		 ak=>Val0,al=>Val0,am=>Val0,an=>Val0,ao=>Val0,
+		 ap=>Val0,aq=>Val0,ar=>Val0,as=>Val0,at=>Val0,
+		 au=>Val0,av=>Val0,aw=>Val0,ax=>Val0,ay=>Val0,
+		 az=>Val0,
+		 K2=>[a,b,c]},
+    Map2 = Map1#{K1=>K1,
+		 a:=Val1,b:=Val1,c:=Val1,d:=Val1,e:=Val1,
+		 f:=Val1,g:=Val1,h:=Val1,i:=Val1,j:=Val1,
+		 k:=Val1,l:=Val1,m:=Val1,n:=Val1,o:=Val1,
+		 p:=Val1,q:=Val1,r:=Val1,s:=Val1,t:=Val1,
+		 u:=Val1,v:=Val1,w:=Val1,x:=Val1,y:=Val1,
+		 z:=Val1,
+		 aa:=Val1,ab:=Val1,ac:=Val1,ad:=Val1,ae:=Val1,
+		 af:=Val1,ag:=Val1,ah:=Val1,ai:=Val1,aj:=Val1,
+		 ak:=Val1,al:=Val1,am:=Val1,an:=Val1,ao:=Val1,
+		 ap:=Val1,aq:=Val1,ar:=Val1,as:=Val1,at:=Val1,
+		 au:=Val1,av:=Val1,aw:=Val1,ax:=Val1,ay:=Val1,
+		 az:=Val1,
+		 K2=>[a,b,c]},
+
+    %% Traverse the maps to validate them.
+    _ = erlang:phash2({Map1,Map2}, 100000),
+
+    _ = {K1,K2,Val0,Val1},			%Force use of Y registers.
+    Map2.
+
+do_badmap(Test) ->
+    Terms = [Test,fun erlang:abs/1,make_ref(),self(),0.0/-1,
+	     <<0:1024>>,<<1:1>>,<<>>,<<1,2,3>>,
+	     [],{a,b,c},[a,b],atom,10.0,42,(1 bsl 65) + 3],
+    [Test(T) || T <- Terms].
diff --git a/lib/dialyzer/test/map_SUITE_data/src/maps_merge.erl b/lib/dialyzer/test/map_SUITE_data/src/maps_merge.erl
new file mode 100644
index 0000000000..d4f3c6887a
--- /dev/null
+++ b/lib/dialyzer/test/map_SUITE_data/src/maps_merge.erl
@@ -0,0 +1,29 @@
+-module(maps_merge).
+
+-export([t1/0, t2/0, t3/0, t4/0, t5/0]).
+
+t1() ->
+    #{a:=1} = maps:merge(#{}, #{}).
+
+t2() ->
+    #{hej := _} = maps:merge(cao(), cio()),
+    #{{} := _} = maps:merge(cao(), cio()).
+
+t3() ->
+    #{a:=1} = maps:merge(cao(), cio()),
+    #{7:=q} = maps:merge(cao(), cio()).
+
+t4() ->
+    #{a:=1} = maps:merge(cio(), cao()),
+    #{7:=q} = maps:merge(cio(), cao()).
+
+t5() ->
+    #{a:=2} = maps:merge(cao(), #{}).
+
+-spec cao() -> #{a := 1, q => none(), 11 => _, atom() => _}.
+cao() ->
+    binary_to_term(<<131,116,0,0,0,3,100,0,1,97,97,1,100,0,1,98,97,9,100,0,1,
+		     102,104,0>>).
+
+-spec cio() -> #{3 := ok, 7 => none(), z => _, integer() => _}.
+cio() -> binary_to_term(<<131,116,0,0,0,2,97,3,100,0,2,111,107,97,9,97,6>>).
diff --git a/lib/dialyzer/test/small_SUITE_data/results/literals b/lib/dialyzer/test/small_SUITE_data/results/literals
index 883e982134..1ee39453a4 100644
--- a/lib/dialyzer/test/small_SUITE_data/results/literals
+++ b/lib/dialyzer/test/small_SUITE_data/results/literals
@@ -14,3 +14,4 @@ literals.erl:26: Matching of pattern {'r', 'a'} tagged with a record name violat
 literals.erl:29: Function m3/1 has no local return
 literals.erl:29: The pattern {{'r', 'a'}} can never match the type any()
 literals.erl:32: Function m4/1 has no local return
+literals.erl:32: Matching of pattern {'r', 'a'} tagged with a record name violates the declared type of #r{id::'integer'}
diff --git a/lib/dialyzer/test/small_SUITE_data/results/maps1 b/lib/dialyzer/test/small_SUITE_data/results/maps1
index 3e076326d2..6cd1c662c4 100644
--- a/lib/dialyzer/test/small_SUITE_data/results/maps1
+++ b/lib/dialyzer/test/small_SUITE_data/results/maps1
@@ -1,4 +1,5 @@
 
 maps1.erl:43: Function t3/0 has no local return
 maps1.erl:46: Function foo/2 has no local return
+maps1.erl:47: A key of type 'beta' cannot exist in a map of type #{'alfa':=42}
 maps1.erl:52: The call Mod:'function'(~{'literal'=>'map'}~,'another_arg') requires that Mod is of type atom() not #{}