1 files changed, 9 insertions, 1 deletions
diff --git a/src/Analysis/Identity.hs b/src/Analysis/Identity.hs
index 54f7cd2..186ab71 100644
--- a/src/Analysis/Identity.hs
+++ b/src/Analysis/Identity.hs
@@ -2,10 +2,12 @@
 {-# LANGUAGE GADTs #-}
 {-# LANGUAGE LambdaCase #-}
 {-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE StandaloneDeriving #-}
 module Analysis.Identity (
-  ValId(..),
   identityAnalysis,
   identityAnalysis',
+  ValId(..),
+  validSplitEither,
 ) where
 
 import Data.Foldable (toList)
@@ -31,6 +33,7 @@ data ValId t where
   VIArr :: Int -> Vec n Int -> ValId (TArr n t)
   VIScal :: Int -> ValId (TScal t)
   VIAccum :: Int -> ValId (TAccum t)
+deriving instance Show (ValId t)
 
 instance PrettyX ValId where
   prettyX = \case
@@ -46,6 +49,11 @@ instance PrettyX ValId where
     VIScal i -> show i
     VIAccum i -> 'C' : show i
 
+validSplitEither :: ValId (TEither a b) -> (Maybe (ValId a), Maybe (ValId b))
+validSplitEither (VIEither (Left v)) = (Just v, Nothing)
+validSplitEither (VIEither (Right v)) = (Nothing, Just v)
+validSplitEither (VIEither' v1 v2) = (Just v1, Just v2)
+
 -- | Symbolic partial evaluation.
 identityAnalysis :: SList STy env -> Expr x env t -> Expr ValId env t
 identityAnalysis env term = runIdGen 0 $ do