Allow named function expressions

Necessary sometimes.  Half of #21.

Author: anko

doc/basics-reference.markdown

@@ -429,6 +429,20 @@ macro compiles to a return-statement.
         return 5 * (a * b);
     };
 
+
+You can also give a name to a function expression as the optional first
+argument, if you so wish.
+
+<!-- !test in named function expression -->
+
+    (var f (function tea () (return "T")))
+
+<!-- !test out named function expression -->
+
+    var f = function tea() {
+        return 'T';
+    };
+
 ### Loops
 
 While-loops (with the `while` macro) take the first argument to be the loop

src/built-in-macros.ls

@@ -298,11 +298,28 @@ contents =
         throw Error "dot called with no arguments"
 
 
-  \function : ({compile, compile-many}:env, params, ...body) ->
+  \function : ({compile, compile-many}:env, ...args) ->
+
+    # The first optional atom argument gives the id that should be attached to
+    # the function expression.  The next argument is the function's argument
+    # list.  All further arguments are statements for the body.
+
+    var id, params
+
+    arg1 = args.shift!
+
+    if arg1 instanceof atom
+      id := type : \Identifier name : arg1.text!
+      params := args.shift! .contents!map compile
+    else
+      # Let's assume it's a list then
+      id := null
+      params := arg1.contents!map compile
+
     type : \FunctionExpression
-    id : null
-    params : params.contents!map compile
-    body : optionally-implicit-block-statement env, body
+    id : id
+    params : params
+    body : optionally-implicit-block-statement env, args
 
   \new : ({compile}, ...args) ->
     [ newTarget, ...newArgs ] = args

test.ls

@@ -166,6 +166,10 @@ test "function expression" ->
   esl "(function (x) (return (+ x 1)))"
     ..`@equals` "(function (x) {\n    return x + 1;\n});"
 
+test "function expression with name" ->
+  esl "(function f (x) (return (+ x 1)))"
+    ..`@equals` "(function f(x) {\n    return x + 1;\n});"
+
 test "function with no arguments" ->
   esl "(function () (return 1))"
     ..`@equals` "(function () {\n    return 1;\n});"