Merge pull request #1419 from rkday/else_multiple_statements

Allow multiple statements in the else branch of for

NEWS

@@ -41,6 +41,8 @@ Changes from 0.13.0
    * `assoc` now evaluates its arguments only once each
    * `break` and `continue` now raise an error when given arguments
      instead of silently ignoring them
+   * Multiple expressions are now allowed in the else clause of
+     a for loop
 
    [ Misc. Improvements ]
    * `read`, `read_str`, and `eval` are exposed and documented as top-level

hy/compiler.py

@@ -1827,12 +1827,8 @@ class HyASTCompiler(object):
         # (for* [] body (else …))
         if expression and expression[-1][0] == HySymbol("else"):
             else_expr = expression.pop()
-            if len(else_expr) > 2:
-                raise HyTypeError(
-                    else_expr,
-                    "`else' statement in `for' is too long")
-            elif len(else_expr) == 2:
-                orel += self.compile(else_expr[1])
+            for else_body in else_expr[1:]:
+                orel += self.compile(else_body)
                 orel += orel.expr_as_stmt()
 
         ret += self.compile(iterable)

tests/compilers/test_ast.py

@@ -337,11 +337,6 @@ def test_ast_valid_for():
     can_compile("(for [a 2] (print a))")
 
 
-def test_ast_invalid_for():
-    "Make sure AST can't compile invalid for"
-    cant_compile("(for* [a 1] (else 1 2))")
-
-
 def test_nullary_break_continue():
     can_compile("(while 1 (break))")
     cant_compile("(while 1 (break 1))")

tests/native_tests/language.hy

@@ -210,6 +210,17 @@
     (else
       (+= count 1)))
   (assert (= count 151))
+
+  (setv count 0)
+  ; multiple statements in the else branch should work
+  (for [x [1 2 3 4 5]
+        y [1 2 3 4 5]]
+    (setv count (+ count x y))
+    (else
+      (+= count 1)
+      (+= count 10)))
+
+  (assert (= count 161))
   (assert (= (list ((fn [] (for [x [[1] [2 3]] y x] (yield y)))))
              (list-comp y [x [[1] [2 3]] y x])))
   (assert (= (list ((fn [] (for [x [[1] [2 3]] y x z (range 5)] (yield z)))))