Eliminate redundant double is_function test

When tuple funs were still supported, the idiom for allowing
real funs with a certain arity but not tuple funs was:

  is_function(Fun) andalso is_function(Fun, Arity)

The reason that both tests were needed is because:

  is_function({M,F}) would return 'false'
  is_function({M,F}, Arity) would return 'true'

In 53ec991d19, is_function/2 was updated to only return 'false'
for tuples, so the call to is_function/1 can be removed.

3 files changed, 17 insertions, 23 deletions

diff --git a/lib/stdlib/src/beam_lib.erl b/lib/stdlib/src/beam_lib.erl
index 6e00401dce..46aaf84d35 100644
--- a/lib/stdlib/src/beam_lib.erl
+++ b/lib/stdlib/src/beam_lib.erl
@@ -972,9 +972,7 @@ handle_call({get_crypto_key, What}, From, #state{crypto_key_f=F}=S) ->
 handle_call({crypto_key_fun, F}, {_,_} = From, S) ->
     case S#state.crypto_key_f of
 	undefined ->
-	    %% Don't allow tuple funs here. (They weren't allowed before,
-	    %% so there is no reason to allow them now.)
-	    if is_function(F), is_function(F, 1) ->
+	    if is_function(F, 1) ->
 		    {Result, Fun, Reply} = 
 			case catch F(init) of
 			    ok ->
diff --git a/lib/stdlib/src/file_sorter.erl b/lib/stdlib/src/file_sorter.erl
index 47adb133b0..aed857aa77 100644
--- a/lib/stdlib/src/file_sorter.erl
+++ b/lib/stdlib/src/file_sorter.erl
@@ -305,7 +305,6 @@ options(Option) ->
 
 options([{format, Format} | L], Opts) when Format =:= binary; 
                                            Format =:= term;
-                                           is_function(Format),
                                            is_function(Format, 1) ->
     options(L, Opts#opts{format = Format});
 options([{format, binary_term} | L], Opts) ->
@@ -324,7 +323,7 @@ options([{tmpdir, Dir} | L],  Opts) ->
         FileName -> 
             options(L, Opts#opts{tmpdir = {dir, FileName}})
     end;
-options([{order, Fun} | L], Opts) when is_function(Fun), is_function(Fun, 2) ->
+options([{order, Fun} | L], Opts) when is_function(Fun, 2) ->
     options(L, Opts#opts{order = Fun});
 options([{order, Order} | L], Opts) when Order =:= ascending; 
                                          Order =:= descending ->
@@ -409,7 +408,7 @@ merge_terms_fun(RFun) ->
             case RFun(read) of
                 end_of_input ->
                     eof;
-                {Objs, NRFun} when is_function(NRFun), is_function(NRFun, 1) ->
+                {Objs, NRFun} when is_function(NRFun, 1) ->
                     {_, [], Ts, _} = fun_objs(Objs, [], 0, ?MAXSIZE, I, W),
                     {{I, Ts, ?CHUNKSIZE}, merge_terms_fun(NRFun)};
                 Error ->
@@ -425,13 +424,12 @@ merge_bins_fun(FileName) ->
             Fun(A)
     end.
 
-wrap_output_terms(term, OutFun, _Z) when is_function(OutFun),
-                                         is_function(OutFun, 1) ->
+wrap_output_terms(term, OutFun, _Z) when is_function(OutFun, 1) ->
     {fun_wterms(OutFun), true};
 wrap_output_terms(term, File, Z) when File =/= undefined ->
     {file_wterms(name, File, Z++[write]), false};
 wrap_output_terms(_Format, Output, _Z) ->
-    {Output, is_function(Output) and is_function(Output, 1)}.
+    {Output, is_function(Output, 1)}.
 
 binary_term_fun() ->
     fun binary_to_term/1.
@@ -1309,8 +1307,7 @@ infun(W) ->
             {end_of_input, W1};
         {end_of_input, Value} ->
             {end_of_input, W1#w{inout_value = {value, Value}}};
-        {Objs, NFun} when is_function(NFun), 
-                          is_function(NFun, 1), 
+        {Objs, NFun} when is_function(NFun, 1),
                           is_list(Objs) ->
             {cont, W#w{in = NFun}, Objs};
         Error ->
@@ -1333,7 +1330,7 @@ outfun(A, W) ->
     try (W#w.out)(A) of
         Reply when A =:= close ->
             Reply;
-        NF when is_function(NF), is_function(NF, 1) ->
+        NF when is_function(NF, 1) ->
             W#w{out = NF};
         Error ->
             error(Error, W1)
@@ -1358,7 +1355,7 @@ is_keyposs([Bad | _]) ->
 is_keyposs(Bad) ->
     {badarg, Bad}.
 
-is_input(Fun) when is_function(Fun), is_function(Fun, 1) ->
+is_input(Fun) when is_function(Fun, 1) ->
     {true, Fun};
 is_input(Files) ->
     is_files(Files).
@@ -1378,7 +1375,7 @@ is_files([], L) ->
 is_files(Bad, _L) ->
     {badarg, Bad}.
 
-maybe_output(Fun) when is_function(Fun), is_function(Fun, 1) ->
+maybe_output(Fun) when is_function(Fun, 1) ->
     {true, Fun};
 maybe_output(File) ->
     case read_file_info(File) of
@@ -1587,7 +1584,6 @@ fun_rterms(InFun) ->
        (read) ->
             case InFun(read) of
                 {Ts, NInFun} when is_list(Ts), 
-                                  is_function(NInFun),
                                   is_function(NInFun, 1) ->
                     {to_bin(Ts, []), fun_rterms(NInFun)};
                 Else ->
@@ -1600,7 +1596,7 @@ fun_wterms(OutFun) ->
             OutFun(close);
        (L) ->
             case OutFun(wterms_arg(L)) of
-                NOutFun when is_function(NOutFun), is_function(NOutFun, 1) ->
+                NOutFun when is_function(NOutFun, 1) ->
                     fun_wterms(NOutFun);
                 Else ->
                     Else
diff --git a/lib/stdlib/src/qlc.erl b/lib/stdlib/src/qlc.erl
index 3ba3a88038..24e64efee7 100644
--- a/lib/stdlib/src/qlc.erl
+++ b/lib/stdlib/src/qlc.erl
@@ -808,21 +808,21 @@ options(Options0, [Key | Keys], L) when is_list(Options0) ->
                 {ok, U};
             {pre_fun, U=undefined} ->
                 {ok, U};
-            {info_fun, Fun} when is_function(Fun), is_function(Fun, 1) ->
+            {info_fun, Fun} when is_function(Fun, 1) ->
                 {ok, Fun};
-            {pre_fun, Fun} when is_function(Fun), is_function(Fun, 1) ->
+            {pre_fun, Fun} when is_function(Fun, 1) ->
                 {ok, Fun};
-            {post_fun, Fun} when is_function(Fun), is_function(Fun, 0) ->
+            {post_fun, Fun} when is_function(Fun, 0) ->
                 {ok, Fun};
-            {lookup_fun, Fun} when is_function(Fun), is_function(Fun, 2) ->
+            {lookup_fun, Fun} when is_function(Fun, 2) ->
                 {ok, Fun};
             {max_lookup, Max} when is_integer(Max), Max >= 0 ->
                 {ok, Max};
             {max_lookup, infinity} ->
                 {ok, -1};
-            {format_fun, Fun} when is_function(Fun), is_function(Fun, 1) ->
+            {format_fun, Fun} when is_function(Fun, 1) ->
                 {ok, Fun};
-            {parent_fun, Fun} when is_function(Fun), is_function(Fun, 0) ->
+            {parent_fun, Fun} when is_function(Fun, 0) ->
                 {ok, Fun};
             {key_equality, KE='=='} ->
                 {ok, KE};
@@ -885,7 +885,7 @@ options(Options0, [Key | Keys], L) when is_list(Options0) ->
             {depth, Depth} when Depth =:= infinity;
                                 is_integer(Depth), Depth >= 0 ->
                 {ok, Depth};
-            {order, Order} when is_function(Order), is_function(Order, 2);
+            {order, Order} when is_function(Order, 2);
                                 (Order =:= ascending);
                                 (Order =:= descending) ->
                 {ok, Order};