Allowing the fat arrow to be used in scoped loops.

lib/nodes.js

@@ -42,7 +42,7 @@
     };
     Base.prototype.compileClosure = function(o) {
       if (this.containsPureStatement()) {
-        throw SyntaxError('cannot include a pure statement in an expression.');
+        throw SyntaxError('cannot use a pure statement in an expression.');
       }
       o.sharedScope = true;
       return Closure.wrap(this).compileNode(o);
@@ -1799,6 +1799,9 @@
       guardPart = '';
       defPart = '';
       idt1 = this.tab + TAB;
+      if (this.scoped && this.containsPureStatement()) {
+        throw SyntaxError('cannot use a pure statement in a scoped loop.');
+      }
       if (this.range) {
         forPart = source.compile(merge(o, {
           index: ivar,

lib/rewriter.js

@@ -176,7 +176,7 @@
         if (prev && !prev.spaced && tag === '?') {
           token.call = true;
         }
-        if (!(callObject || (prev != null ? prev.spaced : void 0) && (prev.call || (_ref3 = prev[0], __indexOf.call(IMPLICIT_FUNC, _ref3) >= 0)) && (__indexOf.call(IMPLICIT_CALL, tag) >= 0 || !(token.spaced || token.newLine) && __indexOf.call(IMPLICIT_UNSPACED_CALL, tag) >= 0) && !(seenFor && tag === '->' && next && next[0] === 'INDENT'))) {
+        if (!(callObject || (prev != null ? prev.spaced : void 0) && (prev.call || (_ref3 = prev[0], __indexOf.call(IMPLICIT_FUNC, _ref3) >= 0)) && (__indexOf.call(IMPLICIT_CALL, tag) >= 0 || !(token.spaced || token.newLine) && __indexOf.call(IMPLICIT_UNSPACED_CALL, tag) >= 0) && !(seenFor && (tag === '->' || tag === '=>') && next && next[0] === 'INDENT'))) {
           return 1;
         }
         tokens.splice(i, 0, ['CALL_START', '(', token[2]]);

src/nodes.coffee

@@ -49,7 +49,7 @@ exports.Base = class Base
   # object with their parent closure, to preserve the expected lexical scope.
   compileClosure: (o) ->
     if @containsPureStatement()
-      throw SyntaxError 'cannot include a pure statement in an expression.'
+      throw SyntaxError 'cannot use a pure statement in an expression.'
     o.sharedScope = yes
     Closure.wrap(this).compileNode o
 
@@ -1454,6 +1454,8 @@ exports.For = class For extends Base
     guardPart     = ''
     defPart       = ''
     idt1          = @tab + TAB
+    if @scoped and @containsPureStatement()
+      throw SyntaxError 'cannot use a pure statement in a scoped loop.'
     if @range
       forPart = source.compile merge(o, {index: ivar, @step})
     else

src/rewriter.coffee

@@ -148,7 +148,7 @@ class exports.Rewriter
       return 1 unless callObject or
         prev?.spaced and (prev.call or prev[0] in IMPLICIT_FUNC) and
         (tag in IMPLICIT_CALL or not (token.spaced or token.newLine) and tag in IMPLICIT_UNSPACED_CALL) and
-        not (seenFor and tag is '->' and next and next[0] is 'INDENT')
+        not (seenFor and tag in ['->', '=>'] and next and next[0] is 'INDENT')
       tokens.splice i, 0, ['CALL_START', '(', token[2]]
       @detectEnd i + 1, (token, i) ->
         return yes if not seenSingle and token.fromThen

test/test_comprehensions.coffee

@@ -139,8 +139,8 @@ ok(num % 2 is 0 for num in array by 2)
 
 # Nested shared scopes.
 foo = ->
-  for i in [0..7] ->
-    for j in [0..7] ->
+  for i in [0..7] =>
+    for j in [0..7] =>
       -> i + j
 
 eq foo()[3][4](), 7