diff --git a/app/Gyehoek/Sexp.hs b/app/Gyehoek/Sexp.hs
index b4bb594..885ff96 100644
--- a/app/Gyehoek/Sexp.hs
+++ b/app/Gyehoek/Sexp.hs
@@ -3,6 +3,7 @@
 {-# LANGUAGE OverloadedStrings #-}
 module Gyehoek.Sexp
   ( let_
+  , sexp
   , nonempty
   , nonEmptyGrammar
   , encode
@@ -11,7 +12,7 @@ module Gyehoek.Sexp
 where
 
 import Data.Text (Text)
-import Language.SexpGrammar as Sexp hiding (List, encode, decode)
+import Language.SexpGrammar as Sexp hiding (List, encode, decode, iso)
 import Language.SexpGrammar qualified as Sexp
 import Language.SexpGrammar.Generic
 import Data.InvertibleGrammar.Base qualified as IGB
@@ -20,11 +21,17 @@ import Data.InvertibleGrammar.Base ((:-)((:-)))
 import Data.List.NonEmpty (NonEmpty ((:|)))
 import Data.List (List)
 import Data.Text.Encoding
+import Data.Either (either)
 import GHC.Generics (Generic)
 import Control.Lens
 
 
-encode :: SexpIso a => a -> Either _ Text
+sexp :: SexpIso a => Iso' a Text
+sexp = iso
+  (either error id . encode)
+  (either error id . decode)
+
+encode :: SexpIso a => a -> Either String Text
 encode = (_Right %~ decodeUtf8 . view strict) . Sexp.encode
 
 decode :: SexpIso a => Text -> Either String a