Make _storeize generic

This allows to change an expression's context to something else than ast.Store if needed.

hy/compiler.py

@@ -534,18 +534,21 @@ class HyASTCompiler(object):
 
         return ret, args, defaults, varargs, kwargs
 
-    def _storeize(self, name):
+    def _storeize(self, name, func=None):
         """Return a new `name` object with an ast.Store() context"""
+        if not func:
+            func = ast.Store
+
         if isinstance(name, Result):
             if not name.is_expr():
-                raise TypeError("Can't assign to a non-expr")
+                raise TypeError("Can't assign / delete a non-expression")
             name = name.expr
 
         if isinstance(name, (ast.Tuple, ast.List)):
             typ = type(name)
             new_elts = []
             for x in name.elts:
-                new_elts.append(self._storeize(x))
+                new_elts.append(self._storeize(x, func))
             new_name = typ(elts=new_elts)
         elif isinstance(name, ast.Name):
             new_name = ast.Name(id=name.id, arg=name.arg)
@@ -554,9 +557,9 @@ class HyASTCompiler(object):
         elif isinstance(name, ast.Attribute):
             new_name = ast.Attribute(value=name.value, attr=name.attr)
         else:
-            raise TypeError("Can't assign to a %s object" % type(name))
+            raise TypeError("Can't assign / delete a %s object" % type(name))
 
-        new_name.ctx = ast.Store()
+        new_name.ctx = func()
         ast.copy_location(new_name, name)
         return new_name