wtf is this

src/Parse.hs

@@ -10,6 +10,7 @@ import Data.Text (Text, unpack)
 import Data.Char (isLetter, isSpace)
 import Data.List (elemIndex)
 import Control.Applicative ((<|>))
+import Control.Monad (guard)
 
 import Syn
 
@@ -28,15 +29,16 @@ parseExpr = parse (parser []) "<FILE>"
 
 parser :: Ctx -> Parser Syn
 parser ctx = do
-  skipSpace
   res <- parseSyn ctx
-  skipSpace
   eof
   pure res
 
 parens :: Parser a -> Parser a
 parens = between (single '(') (single ')')
 
+ns :: Parser a -> Parser a
+ns = between skipSpace skipSpace
+
 opTable :: [[Operator Parser Syn]]
 opTable = 
   [ [ prefix "!" Not
@@ -59,45 +61,31 @@ opTable =
 binary :: Text -> (Syn -> Syn -> Syn) -> Operator Parser Syn
 binary  name f = InfixL  (f <$ chunk name)
 
-prefix, postfix :: Text -> (Syn -> Syn) -> Operator Parser Syn
+prefix :: Text -> (Syn -> Syn) -> Operator Parser Syn
 prefix  name f = Prefix  (f <$ chunk name)
-postfix name f = Postfix (f <$ chunk name)
-
 
 parseSyn :: Ctx -> Parser Syn
-parseSyn ctx = makeExprParser (parseInnerSyn ctx) opTable
+parseSyn ctx = ns (makeExprParser (parseInnerSyn ctx) opTable)
 
 parseInnerSyn :: Ctx -> Parser Syn
 parseInnerSyn ctx = do
-  skipSpace
-  f <- go
-  skipSpace
-  (do
-    x <- try go
-    skipSpace
-    pure (App f x)) <|> pure f
+  l <- many (try (ns goL))
+  r <- many (try (ns goR))
+  let lr = l ++ r
+  guard (not (null lr))
+  pure (foldl1 App lr)
   where 
-    go = choice [ parseFix ctx
-                , parseIf ctx
-                , parseLam ctx
-                , parseLet ctx
-                , parseIL
-                , parseBL
-                , parseUL
-                , parseVar ctx
-                , parens (parseSyn ctx)
-                ]
-
-parseOp :: Text -> Parser Syn -> (Syn -> Syn -> Syn) -> Parser Syn
-parseOp name par op = do
-  a <- par
-  (do
-    skipSpace
-    chunk name
-    skipSpace
-    op a <$> par)
-    <|> pure a
+    goL = choice [ parseIL
+                 , parseBL
+                 , parseUL
+                 , try (parseVar ctx)
+                 , parens (parseSyn ctx)
+                 ]
 
+    goR = choice [ parseIf ctx
+                 , parseLam ctx
+                 , parseLet ctx
+                 ]
 
 parseId :: Parser String
 parseId = unpack <$> P.takeWhile1P Nothing isLetter
@@ -113,23 +101,14 @@ parseBL = (chunk "true"  >> pure (BL True))
       <|> (chunk "false" >> pure (BL False))
 
 parseType :: Parser Ty
-parseType = parseFun
-        <|> parseType1
-
-parseType1 :: Parser Ty
-parseType1 = (chunk "Unit" >> pure Unit)
-         <|> (chunk "Int" >> pure Int)
-         <|> (chunk "Bool" >> pure Bool)
-         <|> parens parseType
-
-parseFun :: Parser Ty
-parseFun = do
-  ty1 <- parseType1 
-  skipSpace
-  chunk "->"
-  skipSpace
-  Fun ty1 <$> parseType
+parseType = ns (makeExprParser (ns parseInnerType) [[ InfixR (Fun <$ chunk "->") ]])
 
+parseInnerType :: Parser Ty
+parseInnerType = choice [ chunk "Unit" >> pure Unit
+                        , chunk "Int" >> pure Int
+                        , chunk "Bool" >> pure Bool
+                        , parens parseType
+                        ]
 
 parseLet :: Ctx -> Parser Syn
 parseLet ctx = do
@@ -181,9 +160,3 @@ parseIf ctx = do
   skipSpace
   b <- parseSyn ctx
   pure (If p a b)
-
-parseFix :: Ctx -> Parser Syn
-parseFix ctx = do
-  chunk "fix"
-  skipSpace
-  Fix <$> parseSyn ctx