Implementing `let'

hy/core/bootstrap.py

@@ -114,3 +114,19 @@ def rest_macro(tree):
     return HyExpression([HySymbol('slice'),
                          ret,
                          HyInteger(1)])
+
+
+@macro("let")
+def let_macro(tree):
+    tree.pop(0)  # "let"
+    ret = tree.pop(0)  # vars
+    # tree is now the body
+    expr = HyExpression([HySymbol("fn"), HyList([])])
+
+    for var in ret:
+        expr.append(HyExpression([HySymbol("setf"), var[0], var[1]]))
+
+    for stmt in tree:
+        expr.append(stmt)
+
+    return HyExpression([expr])

tests/native_tests/language.hy

@@ -294,6 +294,11 @@
   (assert (= (fn-test) 2)))
 
 
+(defn test-let []
+  "NATIVE: test let works rightish"
+  (assert (= (let [[x 1] [y 2] [z 3]] (+ x y z)) 6)))
+
+
 ; FEATURE: native hy-eval
 ;
 ;   - related to bug #64