Generic expression parser with integer operators

1 files changed, 3 insertions, 0 deletions

diff --git a/src/Test.hs b/src/Test.hs
index 16c1b1f..7b9be6f 100644
--- a/src/Test.hs
+++ b/src/Test.hs
@@ -96,6 +96,7 @@ data Expr a where
     Literal :: ExprType a => a -> Expr a
     Concat :: [Expr Text] -> Expr Text
     Regex :: [Expr Text] -> Expr Regex
+    UnOp :: (b -> a) -> Expr b -> Expr a
     BinOp :: (b -> c -> a) -> Expr b -> Expr c -> Expr a
 
 eval :: MonadEval m => Expr a -> m a
@@ -114,6 +115,7 @@ eval (Regex xs) = do
     case compile defaultCompOpt defaultExecOpt $ T.concat $ concat [[T.singleton '^'], parts, [T.singleton '$']] of
         Left err -> fail err
         Right re -> return re
+eval (UnOp f x) = f <$> eval x
 eval (BinOp f x y) = f <$> eval x <*> eval y
 
 gatherVars :: forall a m. MonadEval m => Expr a -> m [(VarName, SomeVarValue)]
@@ -124,4 +126,5 @@ gatherVars = fmap (uniqOn fst . sortOn fst) . helper
     helper (Literal _) = return []
     helper (Concat es) = concat <$> mapM helper es
     helper (Regex es) = concat <$> mapM helper es
+    helper (UnOp _ e) = helper e
     helper (BinOp _ e f) = (++) <$> helper e <*> helper f