for arr: (it) {}

src/parser.zig

@@ -1428,11 +1428,33 @@ pub const Parser = struct {
         self.advance(); // skip 'for'
 
         const iterable = try self.parseExpr();
+
+        // Expect ': (' capture clause
+        try self.expect(.colon);
+        try self.expect(.l_paren);
+
+        // Capture variable name
+        if (self.current.tag != .identifier) return self.fail("expected capture variable name");
+        const capture_name = self.tokenSlice(self.current);
+        self.advance();
+
+        // Optional ', index_name'
+        var index_name: ?[]const u8 = null;
+        if (self.current.tag == .comma) {
+            self.advance();
+            if (self.current.tag != .identifier) return self.fail("expected index variable name");
+            index_name = self.tokenSlice(self.current);
+            self.advance();
+        }
+
+        try self.expect(.r_paren);
         const body = try self.parseBlock();
 
         return try self.createNode(start, .{ .for_expr = .{
             .iterable = iterable,
             .body = body,
+            .capture_name = capture_name,
+            .index_name = index_name,
         } });
     }