Add explicit shell.nix file

1 files changed, 4 insertions, 13 deletions

diff --git a/src/Choc/SimplyTyped.hs b/src/Choc/SimplyTyped.hs
index 3481ec6..cf67b14 100644
--- a/src/Choc/SimplyTyped.hs
+++ b/src/Choc/SimplyTyped.hs
@@ -76,27 +76,18 @@ evalMay t = eval t <$ check [] t
 parseLambda :: Parser Term
 parseLambda = parens $ do
   _ <- reserved "L"
-  t <- parseType
-  b <- parseTerm
-  return $ Lambda t b
+  Lambda <$> parseType <*> parseTerm
 
 parseApp :: Parser Term
-parseApp = parens $ do
-  t1 <- parseTerm
-  t2 <- parseTerm
-  return $ App t1 t2
+parseApp = parens $ App <$> parseTerm <*> parseTerm
 
 parseVar :: Parser Term
 parseVar = Var <$> integer
 
 parseType :: Parser Type
 parseType =
-  (reserved "B" $> Bass) <|>
-  (parens $ do
-      _ <- reservedOp "->"
-      t1 <- parseType
-      t2 <- parseType
-      return (Arrow t1 t2))
+  reserved "B" $> Bass <|>
+  parens (reservedOp "->" >> (Arrow <$> parseType <*> parseType))
 
 parseTerm :: Parser Term
 parseTerm = try parseLambda <|> parseApp <|> parseVar <|> (reserved "C" $> Const)