Got the DRY object pattern matching style working properly, from Harmony. {name, age}: person now works correctly.

lib/grammar.js

@@ -127,7 +127,11 @@
     ],
     // Assignment when it happens within an object literal. The difference from
     // the ordinary **Assign** is that these allow numbers and strings as keys.
-    AssignObj: [o("Identifier ASSIGN Expression", function() {
+    AssignObj: [o("Identifier", function() {
+        return new ValueNode($1);
+      }), o("AlphaNumeric", function() {
+        return new ValueNode($1);
+      }), o("Identifier ASSIGN Expression", function() {
         return new AssignNode(new ValueNode($1), $3, 'object');
       }), o("AlphaNumeric ASSIGN Expression", function() {
         return new AssignNode(new ValueNode($1), $3, 'object');

lib/nodes.js

@@ -937,11 +937,18 @@
       _a = this.variable.base.objects;
       for (i = 0, _b = _a.length; i < _b; i++) {
         obj = _a[i];
+        // A regular array pattern-match.
         idx = i;
         if (this.variable.is_object()) {
-          _c = [obj.value, obj.variable.base];
-          obj = _c[0];
-          idx = _c[1];
+          if (obj instanceof AssignNode) {
+            // A regular object pattern-match.
+            _c = [obj.value, obj.variable.base];
+            obj = _c[0];
+            idx = _c[1];
+          } else {
+            // A shorthand `{a, b, c}: val` pattern-match.
+            idx = obj;
+          }
         }
         if (!(obj instanceof ValueNode || obj instanceof SplatNode)) {
           throw new Error('pattern matching must use only identifiers on the left-hand side.');

src/grammar.coffee

@@ -147,6 +147,8 @@ grammar: {
   # Assignment when it happens within an object literal. The difference from
   # the ordinary **Assign** is that these allow numbers and strings as keys.
   AssignObj: [
+    o "Identifier",                             -> new ValueNode $1
+    o "AlphaNumeric",                           -> new ValueNode $1
     o "Identifier ASSIGN Expression",           -> new AssignNode new ValueNode($1), $3, 'object'
     o "AlphaNumeric ASSIGN Expression",         -> new AssignNode new ValueNode($1), $3, 'object'
     o "Comment"
@@ -448,7 +450,7 @@ grammar: {
     o "IN Expression WHEN Expression",               -> {source: $2, filter: $4}
     o "OF Expression WHEN Expression",               -> {source: $2, filter: $4, object: true}
     o "IN Expression BY Expression",                 -> {source: $2, step:   $4}
-    o "IN Expression WHEN Expression BY Expression", -> {source: $2, filter: $4; step:   $6}
+    o "IN Expression WHEN Expression BY Expression", -> {source: $2, filter: $4, step:   $6}
     o "IN Expression BY Expression WHEN Expression", -> {source: $2, step:   $4, filter: $6}
   ]
 

src/nodes.coffee

@@ -690,8 +690,15 @@ exports.AssignNode: class AssignNode extends BaseNode
     o.as_statement: true
     splat: false
     for obj, i in @variable.base.objects
+      # A regular array pattern-match.
       idx: i
-      [obj, idx]: [obj.value, obj.variable.base] if @variable.is_object()
+      if @variable.is_object()
+        if obj instanceof AssignNode
+          # A regular object pattern-match.
+          [obj, idx]: [obj.value, obj.variable.base]
+        else
+          # A shorthand `{a, b, c}: val` pattern-match.
+          idx: obj
       if not (obj instanceof ValueNode or obj instanceof SplatNode)
         throw new Error 'pattern matching must use only identifiers on the left-hand side.'
       is_string: idx.value and idx.value.match IS_STRING

test/test_pattern_matching.coffee

@@ -89,8 +89,24 @@ test: {
 ok addr.join(', ') is "Street 101, Apt 101, City 101"
 
 
-# Destructuring against an expression.
+# Pattern matching against an expression.
 [a, b]: if true then [2, 1] else [1, 2]
 
 ok a is 2
 ok b is 1
+
+
+# Pattern matching with object shorthand.
+
+person: {
+  name: "Bob"
+  age:  26
+  dogs: ["Prince", "Bowie"]
+}
+
+{name, age, dogs: [first, second]}: person
+
+ok name   is "Bob"
+ok age    is 26
+ok first  is "Prince"
+ok second is "Bowie"