documentation

[fp.git] / src / Lambda.hs

diff --git a/src/Lambda.hs b/src/Lambda.hs
index b3a25ce..3026b75 100644 (file)
--- a/src/Lambda.hs
+++ b/src/Lambda.hs
@@ -14,6 +14,7 @@ module Lambda
   ( -- * Types
     VarName
   , Term(..)
   ( -- * Types
     VarName
   , Term(..)

+  , pattern RedEx

     -- * Reduction
   , alphaNorm
   , reduce
     -- * Reduction
   , alphaNorm
   , reduce


@@ -75,9 +76,9 @@ reduce (App t u) = app (reduce t) u
 
 data Strategy = Eager | Lazy
 
 
 data Strategy = Eager | Lazy
 

-reduceStep :: (Monad m) => Term -> m Term
-reduceStep (RedEx x s t) = return $ substitute x t s
-reduceStep t = return t
+reduceStep :: Term -> Term
+reduceStep (RedEx x s t) = substitute x t s
+reduceStep t = t

 
 data Z = R Term Z | L Z Term | ZL VarName Z | E
 data D = Up | Down
 
 data Z = R Term Z | L Z Term | ZL VarName Z | E
 data D = Up | Down


@@ -96,6 +97,8 @@ unmove :: TermZipper -> TermZipper
 unmove (t, L c r, Down) = (App t r, c, Down)
 unmove x = x
 
 unmove (t, L c r, Down) = (App t r, c, Down)
 unmove x = x
 

+-- getTerm :: TermZipper -> Term
+

 travPost :: (Monad m) => (Term -> m Term) -> Term -> m Term
 travPost fnc term = tr fnc (term, E, Down)
   where 
 travPost :: (Monad m) => (Term -> m Term) -> Term -> m Term
 travPost fnc term = tr fnc (term, E, Down)
   where 


@@ -130,12 +133,13 @@ travPre fnc term = tr fnc (term, E, Down)
 -- >>> toNormalForm Lazy 100 $ (App (App cK cI) cY)
 -- Just (λx.x)
 --
 -- >>> toNormalForm Lazy 100 $ (App (App cK cI) cY)
 -- Just (λx.x)
 --

--- prop> (\ t u -> t == u || t == Nothing || u == Nothing) (alphaNorm <$> toNormalForm Lazy 1000 x) (alphaNorm <$> toNormalForm Eager 1000 x)
+-- prop> within 10000000 $ (\ t u -> t == u || t == Nothing || u == Nothing) (alphaNorm <$> toNormalForm Lazy 1000 x) (alphaNorm <$> toNormalForm Eager 1000 x)

 
 

+-- inf = tRead "(\\d.a ((\\d c.c d c) (\\x y z.x z (y z)) (\\f.(\\x.f (x x)) (\\x.f (x x))) e))"

 
 toNormalForm :: Strategy -> Int -> Term -> Maybe Term
 
 toNormalForm :: Strategy -> Int -> Term -> Maybe Term

-toNormalForm Eager n = flip evalStateT 0 . travPost (cnt >=> short n >=> reduceStep)
-toNormalForm Lazy  n = flip evalStateT 0 . travPre  (cnt >=> short n >=> reduceStep)
+toNormalForm Eager n = flip evalStateT 0 . travPost (cnt >=> short n >=> return . reduceStep)
+toNormalForm Lazy  n = flip evalStateT 0 . travPre  (cnt >=> short n >=> return . reduceStep)

 
 cnt :: (Monad m) => Term -> StateT Int m Term
 cnt t@RedEx{} = do
 
 cnt :: (Monad m) => Term -> StateT Int m Term
 cnt t@RedEx{} = do