1 files changed, 2 insertions, 1 deletions
diff --git a/DSL/Types.hs b/DSL/Types.hs
index bcbe7a6..2faacc4 100644
--- a/DSL/Types.hs
+++ b/DSL/Types.hs
@@ -1,6 +1,7 @@
 module DSL.Types where
 
 import Data.Map.Strict (Map)
+import Data.Void
 
 import DSL.BaseParsers (Parser(..))
 
@@ -56,7 +57,7 @@ data Operation
 
 data StackModifier = StackModifier { smName :: String
                                    , smTypes :: [TypeCheck]
-                                   , smFunc :: Stack -> IO Stack
+                                   , smFunc :: Stack -> IO (Either Void Stack)
                                    }
 
 data Block