Adding in lambdas.

hy/compiler.py

@@ -116,6 +116,28 @@ class HyASTCompiler(object):
                           lineno=e.start_line,
                           col_offset=e.start_column)
 
+    @builds("lambda")
+    def compile_lambda_expression(self, expr):
+        expr.pop(0)
+        sig = expr.pop(0)
+        body = expr.pop(0)
+        # assert expr is empty
+        return ast.Lambda(
+            lineno=expr.start_line,
+            col_offset=expr.start_column,
+            args=ast.arguments(args=[
+                ast.Name(arg=str(x), id=str(x),
+                         ctx=ast.Param(),
+                         lineno=x.start_line,
+                         col_offset=x.start_column)
+                for x in sig],
+                vararg=None,
+                kwarg=None,
+                defaults=[],
+                kwonlyargs=[],
+                kw_defaults=[]),
+            body=self.compile(body))
+
     @builds("get")
     def compile_index_expression(self, expr):
         expr.pop(0)  # index

tests/native_tests/language.hy

@@ -63,3 +63,9 @@
   "NATIVE: Test that dict access works"
   (assert (get {"one" "two"} "one") "two")
   (assert (= (get [1 2 3 4 5] 1) 2)))
+
+
+(defn test_lambda []
+  "NATIVE: test lambda operator"
+  (def square (lambda [x] (* x x)))
+  (assert (= 4 (square 2))))