Implements (raise)

As in Python, this allows to re-raise the last raised exception.

This fixes #86

Signed-off-by: Julien Danjou <julien@danjou.info>

hy/compiler.py

@@ -167,10 +167,10 @@ class HyASTCompiler(object):
 
     @builds("throw")
     @builds("raise")
-    @checkargs(min=1)
+    @checkargs(max=1)
     def compile_throw_expression(self, expr):
         expr.pop(0)
-        exc = self.compile(expr.pop(0))
+        exc = self.compile(expr.pop(0)) if expr else None
         return ast.Raise(
             lineno=expr.start_line,
             col_offset=expr.start_column,

tests/compilers/test_ast.py

@@ -94,22 +94,24 @@ def test_ast_good_do():
 
 def test_ast_good_throw():
     "Make sure AST can compile valid throw"
+    hy_compile(tokenize("(throw)"))
     hy_compile(tokenize("(throw 1)"))
 
 
 def test_ast_bad_throw():
     "Make sure AST can't compile invalid throw"
-    cant_compile("(throw)")
+    cant_compile("(raise 1 2 3)")
 
 
 def test_ast_good_raise():
     "Make sure AST can compile valid raise"
+    hy_compile(tokenize("(raise)"))
     hy_compile(tokenize("(raise 1)"))
 
 
 def test_ast_bad_raise():
     "Make sure AST can't compile invalid raise"
-    cant_compile("(raise)")
+    cant_compile("(raise 1 2 3)")
 
 
 def test_ast_good_try():

tests/native_tests/language.hy

@@ -178,6 +178,26 @@
 
   (try (pass) (except [IOError]) (except))
 
+  ;; Test correct (raise)
+  (let [[passed false]]
+    (try
+      (try
+        (raise IndexError)
+        (except [IndexError] (raise)))
+      (except [IndexError]
+              (setv passed true)))
+    (assert passed))
+
+  ;; Test incorrect (raise)
+  (let [[passed false]]
+    (try
+      (raise)
+      ;; Python 2 raises TypeError
+      ;; Python 3 raises RuntimeError
+      (except [[TypeError RuntimeError]]
+              (setv passed true)))
+    (assert passed))
+
   (try
     (raise (KeyError))
     (catch [[IOError]] (assert false))