works?

src/Parse.hs

@@ -42,7 +42,6 @@ ns = between skipSpace skipSpace
 opTable :: [[Operator Parser Syn]]
 opTable = 
   [ [ prefix "!" Not
-    , prefix "fix" Fix 
     ]
   , [ binary "*" Mul
     , binary "/" Div
@@ -69,8 +68,8 @@ parseSyn ctx = ns (makeExprParser (parseInnerSyn ctx) opTable)
 
 parseInnerSyn :: Ctx -> Parser Syn
 parseInnerSyn ctx = do
-  l <- many (try (ns goL))
-  r <- many (try (ns goR))
+  l <- many (ns goL)
+  r <- many (ns goR)
   let lr = l ++ r
   guard (not (null lr))
   pure (foldl1 App lr)
@@ -85,13 +84,14 @@ parseInnerSyn ctx = do
     goR = choice [ parseIf ctx
                  , parseLam ctx
                  , parseLet ctx
+                 , parseFix ctx
                  ]
 
 parseId :: Parser String
 parseId = unpack <$> P.takeWhile1P Nothing isLetter
 
 parseIL :: Parser Syn
-parseIL = IL <$> L.signed skipSpace (L.lexeme skipSpace L.decimal)
+parseIL = IL <$> L.lexeme skipSpace L.decimal
 
 parseUL :: Parser Syn
 parseUL = chunk "unit" >> pure UL
@@ -146,6 +146,14 @@ parseLam ctx = do
   skipSpace
   Lam <$> parseSyn (name : ctx)
 
+parseFix :: Ctx -> Parser Syn
+parseFix ctx = do
+  chunk "fix"
+  skipSpace
+  res <- parseSyn ctx
+  skipSpace
+  pure (Fix res)
+
 parseIf :: Ctx -> Parser Syn
 parseIf ctx = do
   chunk "if"