Update for fix in Control.Lazy

Author: garyb

docs/Module.md

@@ -31,6 +31,8 @@
 
     instance lazy1ParserT :: Lazy1 (ParserT s m)
 
+    instance lazyParserT :: Lazy (ParserT s m a)
+
     instance monadParserT :: (Monad m) => Monad (ParserT s m)
 
     instance monadPlusParserT :: (Monad m) => MonadPlus (ParserT s m)
@@ -81,10 +83,6 @@
 
     endBy1 :: forall m s a sep. (Monad m) => ParserT s m a -> ParserT s m sep -> ParserT s m [a]
 
-    fix :: forall m s a. (ParserT m s a -> ParserT m s a) -> ParserT m s a
-
-    fix2 :: forall m s a b. (Tuple (ParserT m s a) (ParserT m s b) -> Tuple (ParserT m s a) (ParserT m s b)) -> Tuple (ParserT m s a) (ParserT m s b)
-
     option :: forall m s a. (Monad m) => a -> ParserT s m a -> ParserT s m a
 
     optionMaybe :: forall m s a. (Functor m, Monad m) => ParserT s m a -> ParserT s m (Maybe a)

examples/Test.purs

@@ -8,6 +8,7 @@ import Control.Alt
 import Control.Alternative
 import Control.Monad.Eff
 import Control.Monad.Identity
+import Control.Lazy
 
 import Debug.Trace
 
@@ -20,7 +21,7 @@ parens :: forall m a. (Monad m) => ParserT String m a -> ParserT String m a
 parens = between (string "(") (string ")")
 
 nested :: forall m. (Functor m, Monad m) => ParserT String m Number
-nested = fix $ \p -> (do
+nested = fix1 $ \p -> (do
   string "a"
   return 0) <|> ((+) 1) <$> parens p
 

src/Text/Parsing/Parser.purs

@@ -84,6 +84,9 @@ instance monadStateParserT :: (Monad m) => MonadState s (ParserT s m) where
     return $ case f s of
       Tuple a s' -> { input: s', consumed: false, result: Right a }
 
+instance lazyParserT :: Lazy (ParserT s m a) where
+  defer f = ParserT $ \s -> unParserT (f unit) s
+
 instance lazy1ParserT :: Lazy1 (ParserT s m) where
   defer1 f = ParserT $ \s -> unParserT (f unit) s
 

src/Text/Parsing/Parser/Combinators.purs

@@ -7,6 +7,7 @@ import Data.Either
 
 import Control.Alt
 import Control.Alternative
+import Control.Lazy
 import Control.Monad
 import Control.Monad.Error.Trans
 import Control.Monad.Error.Class
@@ -15,14 +16,6 @@ import Control.Monad.State.Class
 
 import Text.Parsing.Parser
 
-fix :: forall m s a. (ParserT m s a -> ParserT m s a) -> ParserT m s a
-fix f = ParserT $ \s -> unParserT (f (fix f)) s
-
-fix2 :: forall m s a b. (Tuple (ParserT m s a) (ParserT m s b) -> Tuple (ParserT m s a) (ParserT m s b)) -> Tuple (ParserT m s a) (ParserT m s b)
-fix2 f = Tuple
-           (ParserT $ \s -> unParserT (fst (f (fix2 f))) s)
-           (ParserT $ \s -> unParserT (snd (f (fix2 f))) s)
-
 (<?>) :: forall m s a. (Monad m) => ParserT s m a -> String -> ParserT s m a
 (<?>) p msg = p <|> fail ("Expected " ++ msg)