1 files changed, 4 insertions, 0 deletions

diff --git a/src/Sequence/Formula.hs b/src/Sequence/Formula.hs
index ca945f8..4f2e61b 100644
--- a/src/Sequence/Formula.hs
+++ b/src/Sequence/Formula.hs
@@ -28,6 +28,7 @@ import Data.Bool
 import Data.List
 import Data.Maybe
 import Data.Either
+import Data.Tuple
 
 import Data.Set (Set)
 import qualified Data.Set as Set
@@ -109,6 +110,9 @@ evalFormula = evalFormula' []
         Left q@(Question{..}) -> askQuestion promptPref input q >>= flip (flip evalFormula' promptPref $ bool (pure . set (ctx' . answer) $ throwError q) mempty keepResult ++ finalChanges) formula
         Right result -> return (foldr ($) input finalChanges, result)
 
+evalFormula' :: (MonadIO m, sInput :<: lInput, MonadState lInput m) => String -> FormulaM sInput a -> m a
+evalFormula' promptPref formula = uncurry (<$) . over _2 put . swap =<< flip (evalFormula promptPref) formula =<< get
+
 val :: Integral a => Traversal' input (Formula input) -> String -> Bool -> Formula input
 val answer prompt keepResult = do
   gets (Set.member prompt) >>= bool (modify $ Set.insert prompt) (modify (Set.delete prompt) >> throwError Question{..})