compiler: Use expressions in core patterns

Two patterns, binary_segment size and map_pair key, are expressions
even in matching. If only bound variables are used we are fine but
some expressions which appears as literals needs to be lifted.

Currently only Map key binaries will use this.

1 files changed, 146 insertions, 95 deletions

diff --git a/lib/compiler/src/v3_core.erl b/lib/compiler/src/v3_core.erl
index 348ef9051d..dd835a6a9f 100644
--- a/lib/compiler/src/v3_core.erl
+++ b/lib/compiler/src/v3_core.erl
@@ -187,43 +187,63 @@ function({function,_,Name,Arity,Cs0}, Ws0, File, Opts) ->
 body(Cs0, Name, Arity, St0) ->
     Anno = lineno_anno(element(2, hd(Cs0)), St0),
     {Args,St1} = new_vars(Anno, Arity, St0),
-    {Cs1,St2} = clauses(Cs0, St1),
-    {Ps,St3} = new_vars(Arity, St2),    %Need new variables here
-    Fc = function_clause(Ps, Anno, {Name,Arity}),
-    {#ifun{anno=#a{anno=Anno},id=[],vars=Args,clauses=Cs1,fc=Fc},St3}.
+    case clauses(Cs0, St1) of
+	{Cs1,[],St2} ->
+	    {Ps,St3} = new_vars(Arity, St2),    %Need new variables here
+	    Fc = function_clause(Ps, Anno, {Name,Arity}),
+	    {#ifun{anno=#a{anno=Anno},id=[],vars=Args,clauses=Cs1,fc=Fc},St3};
+	{Cs1,Eps,St2} ->
+	    %% We have pre-expressions from patterns and
+	    %% these needs to be letified before matching
+	    %% since only bound variables are allowed
+	    AnnoGen = #a{anno=[compiler_generated]},
+	    {Ps1,St3} = new_vars(Arity, St2),    %Need new variables here
+	    Fc1 = function_clause(Ps1, Anno, {Name,Arity}),
+	    {Ps2,St4} = new_vars(Arity, St3),    %Need new variables here
+	    Fc2 = function_clause(Ps2, Anno, {Name,Arity}),
+	    Case = #icase{anno=AnnoGen,args=Args,
+			  clauses=Cs1,
+			  fc=Fc2},
+	    {#ifun{anno=#a{anno=Anno},id=[],vars=Args,
+		   clauses=[#iclause{anno=AnnoGen,pats=Ps1,
+				     guard=[#c_literal{val=true}],
+				     body=Eps ++ [Case]}],
+		   fc=Fc1},St4}
+    end.
 
 %% clause(Clause, State) -> {Cclause,State} | noclause.
 %% clauses([Clause], State) -> {[Cclause],State}.
 %%  Convert clauses.  Trap bad pattern aliases and remove clause from
 %%  clause list.
 
-clauses([C0|Cs0], St0) ->
+clauses([C0|Cs0],St0) ->
     case clause(C0, St0) of
-	{noclause,St} -> clauses(Cs0, St);
-	{C,St1} ->
-	    {Cs,St2} = clauses(Cs0, St1),
-	    {[C|Cs],St2}
+	{noclause,_,St} -> clauses(Cs0,St);
+	{C,Eps1,St1} ->
+	    {Cs,Eps2,St2} = clauses(Cs0, St1),
+	    {[C|Cs],Eps1++Eps2,St2}
     end;
-clauses([], St) -> {[],St}.
+clauses([],St) -> {[],[],St}.
 
 clause({clause,Lc,H0,G0,B0}, St0) ->
     try head(H0, St0) of
-	H1 ->
-	    {G1,St1} = guard(G0, St0),
-	    {B1,St2} = exprs(B0, St1),
-            Anno = lineno_anno(Lc, St2),
-	    {#iclause{anno=#a{anno=Anno},pats=H1,guard=G1,body=B1},St2}
+	{H1,Eps,St1} ->
+	    {G1,St2} = guard(G0, St1),
+	    {B1,St3} = exprs(B0, St2),
+            Anno = lineno_anno(Lc, St3),
+	    {#iclause{anno=#a{anno=Anno},pats=H1,guard=G1,body=B1},Eps,St3}
     catch
 	throw:nomatch ->
 	    St = add_warning(Lc, nomatch, St0),
-	    {noclause,St}			%Bad pattern
+	    {noclause,[],St}			%Bad pattern
     end.
 
 clause_arity({clause,_,H0,_,_}) -> length(H0).
 
-%% head([P], State) -> [P].
+%% head([P], State) -> {[P],[Cexpr],State}.
 
-head(Ps, St) -> pattern_list(Ps, St).
+head(Ps, St) ->
+    pattern_list(Ps, St).
 
 %% guard([Expr], State) -> {[Cexpr],State}.
 %%  Build an explict and/or tree of guard alternatives, then traverse
@@ -548,26 +568,26 @@ expr({block,_,Es0}, St0) ->
     {E1,Eps,St2} = expr(last(Es0), St1),
     {E1,Es1 ++ Eps,St2};
 expr({'if',L,Cs0}, St0) ->
-    {Cs1,St1} = clauses(Cs0, St0),
+    {Cs1,Ceps,St1} = clauses(Cs0, St0),
     Lanno = lineno_anno(L, St1),
     Fc = fail_clause([], Lanno, #c_literal{val=if_clause}),
-    {#icase{anno=#a{anno=Lanno},args=[],clauses=Cs1,fc=Fc},[],St1};
+    {#icase{anno=#a{anno=Lanno},args=[],clauses=Cs1,fc=Fc},Ceps,St1};
 expr({'case',L,E0,Cs0}, St0) ->
     {E1,Eps,St1} = novars(E0, St0),
-    {Cs1,St2} = clauses(Cs0, St1),
+    {Cs1,Ceps,St2} = clauses(Cs0, St1),
     {Fpat,St3} = new_var(St2),
     Lanno = lineno_anno(L, St2),
     Fc = fail_clause([Fpat], Lanno, c_tuple([#c_literal{val=case_clause},Fpat])),
-    {#icase{anno=#a{anno=Lanno},args=[E1],clauses=Cs1,fc=Fc},Eps,St3};
+    {#icase{anno=#a{anno=Lanno},args=[E1],clauses=Cs1,fc=Fc},Eps++Ceps,St3};
 expr({'receive',L,Cs0}, St0) ->
-    {Cs1,St1} = clauses(Cs0, St0),
-    {#ireceive1{anno=#a{anno=lineno_anno(L, St1)},clauses=Cs1}, [], St1};
+    {Cs1,Ceps,St1} = clauses(Cs0, St0),
+    {#ireceive1{anno=#a{anno=lineno_anno(L, St1)},clauses=Cs1},Ceps, St1};
 expr({'receive',L,Cs0,Te0,Tes0}, St0) ->
     {Te1,Teps,St1} = novars(Te0, St0),
     {Tes1,St2} = exprs(Tes0, St1),
-    {Cs1,St3} = clauses(Cs0, St2),
+    {Cs1,Ceps,St3} = clauses(Cs0, St2),
     {#ireceive2{anno=#a{anno=lineno_anno(L, St3)},
-		clauses=Cs1,timeout=Te1,action=Tes1},Teps,St3};
+		clauses=Cs1,timeout=Te1,action=Tes1},Teps++Ceps,St3};
 expr({'try',L,Es0,[],Ecs,[]}, St0) ->
     %% 'try ... catch ... end'
     {Es1,St1} = exprs(Es0, St0),
@@ -581,7 +601,7 @@ expr({'try',L,Es0,Cs0,Ecs,[]}, St0) ->
     %% 'try ... of ... catch ... end'
     {Es1,St1} = exprs(Es0, St0),
     {V,St2} = new_var(St1),		%This name should be arbitrary
-    {Cs1,St3} = clauses(Cs0, St2),
+    {Cs1,Ceps,St3} = clauses(Cs0, St2),
     {Fpat,St4} = new_var(St3),
     Lanno = lineno_anno(L, St4),
     Fc = fail_clause([Fpat], Lanno,
@@ -590,7 +610,7 @@ expr({'try',L,Es0,Cs0,Ecs,[]}, St0) ->
     {#itry{anno=#a{anno=lineno_anno(L, St5)},args=Es1,
 	   vars=[V],body=[#icase{anno=#a{anno=Lanno},args=[V],clauses=Cs1,fc=Fc}],
 	   evars=Evs,handler=Hs},
-     [],St5};
+     Ceps,St5};
 expr({'try',L,Es0,[],[],As0}, St0) ->
     %% 'try ... after ... end'
     {Es1,St1} = exprs(Es0, St0),
@@ -659,24 +679,24 @@ expr({match,L,P0,E0}, St0) ->
 	      {var,_,'_'} -> St0#core{wanted=false};
 	      _ -> St0
 	  end,
-    {E2,Eps,St2} = novars(E1, St1),
+    {E2,Eps1,St2} = novars(E1, St1),
     St3 = St2#core{wanted=St0#core.wanted},
-    P2 = try
-	     pattern(P1, St3)
+    {P2,Eps2,St4} = try
+	    pattern(P1, St3)
 	 catch
 	     throw:Thrown ->
-		 Thrown
+		{Thrown,[],St3}
 	 end,
-    {Fpat,St4} = new_var(St3),
-    Lanno = lineno_anno(L, St4),
+    {Fpat,St5} = new_var(St4),
+    Lanno = lineno_anno(L, St5),
     Fc = fail_clause([Fpat], Lanno, c_tuple([#c_literal{val=badmatch},Fpat])),
     case P2 of
 	nomatch ->
-	    St = add_warning(L, nomatch, St4),
+	    St = add_warning(L, nomatch, St5),
 	    {#icase{anno=#a{anno=Lanno},
-		    args=[E2],clauses=[],fc=Fc},Eps,St};
+		    args=[E2],clauses=[],fc=Fc},Eps1++Eps2,St};
 	Other when not is_atom(Other) ->
-	    {#imatch{anno=#a{anno=Lanno},pat=P2,arg=E2,fc=Fc},Eps,St4}
+	    {#imatch{anno=#a{anno=Lanno},pat=P2,arg=E2,fc=Fc},Eps1++Eps2,St5}
     end;
 expr({op,_,'++',{lc,Llc,E,Qs0},More}, St0) ->
     %% Optimise '++' here because of the list comprehension algorithm.
@@ -828,7 +848,7 @@ is_valid_map_src(_)         -> false.
 try_exception(Ecs0, St0) ->
     %% Note that Tag is not needed for rethrow - it is already in Info.
     {Evs,St1} = new_vars(3, St0), % Tag, Value, Info
-    {Ecs1,St2} = clauses(Ecs0, St1),
+    {Ecs1,Ceps,St2} = clauses(Ecs0, St1),
     [_,Value,Info] = Evs,
     Ec = #iclause{anno=#a{anno=[compiler_generated]},
 		  pats=[c_tuple(Evs)],guard=[#c_literal{val=true}],
@@ -836,15 +856,15 @@ try_exception(Ecs0, St0) ->
 				 name=#c_literal{val=raise},
 				 args=[Info,Value]}]},
     Hs = [#icase{anno=#a{},args=[c_tuple(Evs)],clauses=Ecs1,fc=Ec}],
-    {Evs,Hs,St2}.
+    {Evs,Ceps++Hs,St2}.
 
 try_after(As, St0) ->
     %% See above.
-    {Evs,St1} = new_vars(3, St0),		% Tag, Value, Info
+    {Evs,St1} = new_vars(3, St0),	 % Tag, Value, Info
     [_,Value,Info] = Evs,
-    B = As ++ [#iprimop{anno=#a{},       %Must have an #a{}
-			 name=#c_literal{val=raise},
-			 args=[Info,Value]}],
+    B = As ++ [#iprimop{anno=#a{},       % Must have an #a{}
+			name=#c_literal{val=raise},
+			args=[Info,Value]}],
     Ec = #iclause{anno=#a{anno=[compiler_generated]},
 		  pats=[c_tuple(Evs)],guard=[#c_literal{val=true}],
 		  body=B},
@@ -978,7 +998,7 @@ bitstr({bin_element,_,E0,Size0,[Type,{unit,Unit}|Flags]}, St0) ->
 
 fun_tq({_,_,Name}=Id, Cs0, L, St0, NameInfo) ->
     Arity = clause_arity(hd(Cs0)),
-    {Cs1,St1} = clauses(Cs0, St0),
+    {Cs1,Ceps,St1} = clauses(Cs0, St0),
     {Args,St2} = new_vars(Arity, St1),
     {Ps,St3} = new_vars(Arity, St2),		%Need new variables here
     Anno = lineno_anno(L, St3),
@@ -986,7 +1006,7 @@ fun_tq({_,_,Name}=Id, Cs0, L, St0, NameInfo) ->
     Fun = #ifun{anno=#a{anno=Anno},
 		id=[{id,Id}],				%We KNOW!
 		vars=Args,clauses=Cs1,fc=Fc,name=NameInfo},
-    {Fun,[],St3}.
+    {Fun,Ceps,St3}.
 
 %% lc_tq(Line, Exp, [Qualifier], Mc, State) -> {LetRec,[PreExp],State}.
 %%  This TQ from Simon PJ pp 127-138.  
@@ -1200,7 +1220,7 @@ is_generator(_) -> false.
 generator(Line, {generate,Lg,P0,E}, Gs, St0) ->
     LA = lineno_anno(Line, St0),
     GA = lineno_anno(Lg, St0),
-    {Head,St1} = list_gen_pattern(P0, Line, St0),
+    {Head,Ceps,St1} = list_gen_pattern(P0, Line, St0),
     {[Tail,Skip],St2} = new_vars(2, St1),
     {Cg,St3} = lc_guard_tests(Gs, St2),
     {AccPat,SkipPat} = case Head of
@@ -1221,24 +1241,25 @@ generator(Line, {generate,Lg,P0,E}, Gs, St0) ->
                        end,
     {Ce,Pre,St4} = safe(E, St3),
     Gen = #igen{anno=#a{anno=GA},acc_pat=AccPat,acc_guard=Cg,skip_pat=SkipPat,
-                tail=Tail,tail_pat=#c_literal{anno=LA,val=[]},arg={Pre,Ce}},
+                tail=Tail,tail_pat=#c_literal{anno=LA,val=[]},arg={Ceps++Pre,Ce}},
     {Gen,St4};
 generator(Line, {b_generate,Lg,P,E}, Gs, St0) ->
     LA = lineno_anno(Line, St0),
     GA = lineno_anno(Lg, St0),
-    Cp = #c_binary{segments=Segs} = pattern(P, St0),
+    {Cp = #c_binary{segments=Segs},[],St1} = pattern(P, St0),
+    
     %% The function append_tail_segment/2 keeps variable patterns as-is, making
     %% it possible to have the same skip clause removal as with list generators.
-    {AccSegs,Tail,TailSeg,St1} = append_tail_segment(Segs, St0),
+    {AccSegs,Tail,TailSeg,St2} = append_tail_segment(Segs, St1),
     AccPat = Cp#c_binary{segments=AccSegs},
-    {Cg,St2} = lc_guard_tests(Gs, St1),
-    {SkipSegs,St3} = emasculate_segments(AccSegs, St2),
+    {Cg,St3} = lc_guard_tests(Gs, St2),
+    {SkipSegs,St4} = emasculate_segments(AccSegs, St3),
     SkipPat = Cp#c_binary{segments=SkipSegs},
-    {Ce,Pre,St4} = safe(E, St3),
+    {Ce,Pre,St5} = safe(E, St4),
     Gen = #igen{anno=#a{anno=GA},acc_pat=AccPat,acc_guard=Cg,skip_pat=SkipPat,
                 tail=Tail,tail_pat=#c_binary{anno=LA,segments=[TailSeg]},
                 arg={Pre,Ce}},
-    {Gen,St4}.
+    {Gen,St5}.
 
 append_tail_segment(Segs, St0) ->
     {Var,St} = new_var(St0),
@@ -1267,9 +1288,9 @@ lc_guard_tests(Gs0, St0) ->
 
 list_gen_pattern(P0, Line, St) ->
     try
-	{pattern(P0, St),St}
+	pattern(P0,St)
     catch 
-	nomatch -> {nomatch,add_warning(Line, nomatch, St)}
+	nomatch -> {nomatch,[],add_warning(Line, nomatch, St)}
     end.
 
 %%%
@@ -1492,6 +1513,18 @@ force_novars(#ibinary{}=Bin, St) -> {Bin,[],St};
 force_novars(Ce, St) ->
     force_safe(Ce, St).
 
+
+%% safe_pattern_expr(Expr, State) -> {Cexpr,[PreExpr],State}.
+%%   only literals and variables are safe expressions in patterns
+safe_pattern_expr(E,St0) ->
+    case safe(E,St0) of
+	{#c_var{},_,_}=Safe -> Safe;
+	{#c_literal{},_,_}=Safe -> Safe;
+	{Ce,Eps,St1} ->
+	    {V,St2} = new_var(St1),
+	    {V,Eps++[#iset{var=V,arg=Ce}],St2}
+    end.
+
 %% safe(Expr, State) -> {Safe,[PreExpr],State}.
 %%  Generate an internal safe expression.  These are simples without
 %%  binaries which can fail.  At this level we do not need to do a
@@ -1566,46 +1599,61 @@ fold_match({match,L,P0,E0}, P) ->
     {{match,L,P0,P1},E1};
 fold_match(E, P) -> {P,E}.
 
-%% pattern(Pattern, State) -> CorePat.
+%% pattern(Pattern, State) -> {CorePat,[PreExp],State}.
 %% Transform a pattern by removing line numbers.  We also normalise
 %% aliases in patterns to standard form, {alias,Pat,[Var]}.
-
-pattern({var,L,V}, St) -> #c_var{anno=lineno_anno(L, St),name=V};
-pattern({char,L,C}, St) -> #c_literal{anno=lineno_anno(L, St),val=C};
-pattern({integer,L,I}, St) -> #c_literal{anno=lineno_anno(L, St),val=I};
-pattern({float,L,F}, St) -> #c_literal{anno=lineno_anno(L, St),val=F};
-pattern({atom,L,A}, St) -> #c_literal{anno=lineno_anno(L, St),val=A};
-pattern({string,L,S}, St) -> #c_literal{anno=lineno_anno(L, St),val=S};
-pattern({nil,L}, St) -> #c_literal{anno=lineno_anno(L, St),val=[]};
+%%
+%% In patterns we may have expressions
+%% 1) Binaries -> #c_bitstr{size=Expr}
+%% 2) Maps -> #c_map_pair{key=Expr}
+%%
+%% Both of these may generate pre-expressions since only bound variables
+%% or literals are allowed for these in core patterns.
+%%
+%% Therefor, we need to drag both the state and the collection of pre-expression
+%% around in the whole pattern transformation tree.
+
+pattern({var,L,V}, St) -> {#c_var{anno=lineno_anno(L, St),name=V},[],St};
+pattern({char,L,C}, St) -> {#c_literal{anno=lineno_anno(L, St),val=C},[],St};
+pattern({integer,L,I}, St) -> {#c_literal{anno=lineno_anno(L, St),val=I},[],St};
+pattern({float,L,F}, St) -> {#c_literal{anno=lineno_anno(L, St),val=F},[],St};
+pattern({atom,L,A}, St) -> {#c_literal{anno=lineno_anno(L, St),val=A},[],St};
+pattern({string,L,S}, St) -> {#c_literal{anno=lineno_anno(L, St),val=S},[],St};
+pattern({nil,L}, St) -> {#c_literal{anno=lineno_anno(L, St),val=[]},[],St};
 pattern({cons,L,H,T}, St) ->
-    annotate_cons(lineno_anno(L, St), pattern(H, St), pattern(T, St), St);
+    {Ph,Eps1,St1} = pattern(H, St),
+    {Pt,Eps2,St2} = pattern(T, St1),
+    {annotate_cons(lineno_anno(L, St), Ph, Pt, St2),Eps1++Eps2,St2};
 pattern({tuple,L,Ps}, St) ->
-    annotate_tuple(record_anno(L, St), pattern_list(Ps, St), St);
-pattern({map,L,Ps}, St) ->
-    #c_map{anno=lineno_anno(L, St), es=pattern_map_pairs(Ps, St)};
+    {Ps1,Eps,St1} = pattern_list(Ps,St),
+    {annotate_tuple(record_anno(L, St), Ps1, St),Eps,St1};
+pattern({map,L,Pairs}, St0) ->
+    {Ps,Eps,St1} = pattern_map_pairs(Pairs, St0),
+    {#c_map{anno=lineno_anno(L, St1), es=Ps},Eps,St1};
 pattern({bin,L,Ps}, St) ->
     %% We don't create a #ibinary record here, since there is
     %% no need to hold any used/new annotations in a pattern.
-    #c_binary{anno=lineno_anno(L, St),segments=pat_bin(Ps, St)};
+    {#c_binary{anno=lineno_anno(L, St),segments=pat_bin(Ps, St)},[],St};
 pattern({match,_,P1,P2}, St) ->
-    pat_alias(pattern(P1, St), pattern(P2, St)).
+    {Cp1,[],St1} = pattern(P1, St),
+    {Cp2,[],St2} = pattern(P2, St1),
+    {pat_alias(Cp1,Cp2),[],St2}.
 
 %% pattern_map_pairs([MapFieldExact],State) -> [#c_map_pairs{}]
 pattern_map_pairs(Ps, St) ->
     %% check literal key uniqueness (dict is needed)
     %% pattern all pairs
-    {CMapPairs, Kdb} = lists:mapfoldl(fun
-	    (P,Kdbi) ->
-		#c_map_pair{key=Ck,val=Cv} = CMapPair = pattern_map_pair(P,St),
+    {CMapPairs, {Kdb,Eps,St1}} = lists:mapfoldl(fun
+	    (P,{Kdbi,EpsM,Sti0}) ->
+		{CMapPair,EpsP,Sti1} = pattern_map_pair(P,Sti0),
+		#c_map_pair{key=Ck,val=Cv} = CMapPair,
 		K = pattern_map_clean_key(Ck),
 		case dict:find(K,Kdbi) of
-		    {ok, Vs} ->
-			{CMapPair, dict:store(K,[Cv|Vs],Kdbi)};
-		    _ ->
-			{CMapPair, dict:store(K,[Cv],Kdbi)}
+		    {ok, Vs} -> {CMapPair, {dict:store(K,[Cv|Vs],Kdbi),EpsM++EpsP,Sti1}};
+		    _ ->        {CMapPair, {dict:store(K,[Cv],Kdbi),EpsM++EpsP,Sti1}}
 		end
-	end, dict:new(), Ps),
-    pattern_alias_map_pairs(CMapPairs,Kdb,dict:new(),St).
+	end, {dict:new(),[],St}, Ps),
+    {pattern_alias_map_pairs(CMapPairs,Kdb,dict:new(),St1),Eps,St1}.
 
 %% remove cluddering annotations
 pattern_map_clean_key(#c_literal{val=V}) -> {literal,V};
@@ -1630,25 +1678,22 @@ pattern_alias_map_pair_patterns([Cv]) -> Cv;
 pattern_alias_map_pair_patterns([Cv1,Cv2|Cvs]) ->
     pattern_alias_map_pair_patterns([pat_alias(Cv1,Cv2)|Cvs]).
 
-pattern_map_pair({map_field_exact,L,K,V}, St) ->
-    %% guard against pre-expressions
-    %% i.e. keys like {atom, <<0:300>>} where
-    %% <<0:300>> becomes a pre-expression
-    case expr(K,St) of
-	{Ck,[],_} ->
-	    #c_map_pair{anno=lineno_anno(L,St),
-			op=#c_literal{val=exact},
-			key=Ck,
-			val=pattern(V,St)};
-	_ -> erlang:throw(nomatch)
-    end.
+pattern_map_pair({map_field_exact,L,K,V}, St0) ->
+    {Ck,EpsK,St1} = safe_pattern_expr(K,St0),
+    {Cv,EpsV,St2} = pattern(V, St1),
+    {#c_map_pair{anno=lineno_anno(L,St2),
+		 op=#c_literal{val=exact},
+		 key=Ck,
+		 val=Cv},EpsK++EpsV,St2}.
 
 %% pat_bin([BinElement], State) -> [BinSeg].
 
 pat_bin(Ps, St) -> [pat_segment(P, St) || P <- Ps].
 
-pat_segment({bin_element,_,Term,Size,[Type,{unit,Unit}|Flags]}, St) ->
-    #c_bitstr{val=pattern(Term, St),size=pattern(Size, St),
+pat_segment({bin_element,_,Val,Size,[Type,{unit,Unit}|Flags]}, St) ->
+    {Pval,[],St1} = pattern(Val,St),
+    {Psize,[],_St2} = pattern(Size,St1),
+    #c_bitstr{val=Pval,size=Psize,
 	      unit=#c_literal{val=Unit},
 	      type=#c_literal{val=Type},
 	      flags=#c_literal{val=Flags}}.
@@ -1696,9 +1741,15 @@ pat_alias_list([A1|A1s], [A2|A2s]) ->
 pat_alias_list([], []) -> [];
 pat_alias_list(_, _) -> throw(nomatch).
 
-%% pattern_list([P], State) -> [P].
+%% pattern_list([P], State) -> {[P],Exprs,St}
+
+pattern_list([P0|Ps0], St0) ->
+    {P1,Eps,St1} = pattern(P0, St0),
+    {Ps1,Epsl,St2} = pattern_list(Ps0, St1),
+    {[P1|Ps1], Eps ++ Epsl, St2};
+pattern_list([], St) ->
+    {[],[],St}.
 
-pattern_list(Ps, St) -> [pattern(P, St) || P <- Ps].
 
 %% make_vars([Name]) -> [{Var,Name}].