reenable tests

[fp.git] / src / Lambda.hs

diff --git a/src/Lambda.hs b/src/Lambda.hs
index 07d1f4b..b3a25ce 100644 (file)
--- a/src/Lambda.hs
+++ b/src/Lambda.hs
@@ -1,4 +1,3 @@
-{-# OPTIONS_GHC -fno-warn-unused-do-bind #-}

 {-# LANGUAGE PatternSynonyms #-}
 
 -- |
 {-# LANGUAGE PatternSynonyms #-}
 
 -- |


@@ -15,131 +14,33 @@ module Lambda
   ( -- * Types
     VarName
   , Term(..)
   ( -- * Types
     VarName
   , Term(..)

-    -- * Parsing terms
-  , parseTerm
-  , tRead

     -- * Reduction
     -- * Reduction

+  , alphaNorm

   , reduce
   , toNormalForm
   , Strategy(..)
   ) where
   , reduce
   , toNormalForm
   , Strategy(..)
   ) where

-  

 
 

-import Data.Text as T hiding (map)
-import Data.Attoparsec.Text
-import Control.Applicative

 import Control.Monad.State 
 
 import Control.Monad.State 
 

+import Lambda.Term
+

 -- $setup
 -- $setup

--- >>> import Test.QuickCheck

 -- >>> import Control.Applicative
 -- >>> import Control.Applicative

--- >>> let aVarName = oneof . map (pure . (:[])) $ ['a'..'e']
--- >>> let aVar = liftA Var aVarName
--- >>> let aComb = oneof . map pure $ [cS, cK, cI, cY]
--- >>> let aTerm 0 = aVar 
--- >>> let aTerm n = oneof [aVar, aComb, liftA2 Lambda aVarName $ aTerm (n - 1), liftA2 App (aTerm (n `div` 2)) (aTerm (n `div` 2))] 
--- >>> instance Arbitrary Term where arbitrary = sized aTerm
---
--- TODO: shrink Terms
-
-cP :: Term
-cP = tRead "(λa d c.(λa.e) b (λc.d)) ((λa.(λd.a) (λd c.b ((λa.a) a)) (a ((λa.(λd.e) ((λe.(λd b.a) (λa c.(λa a d.(λd.b (λa d.c) e) (λb b.c a (a d (λb d d e a.d (λb b.d))))) ((λb.a) c)) (d ((λc.(λd.a (λe.e)) (c d)) ((λe.b) a))) c (λa.d (e (λe.(λd c.b) a))) (c (b a)) a (λe.(λa b e b a.d) b)) ((λe.b) (λa.b)) ((λe d.b) b) e) b) ((λc c.a e) (λb.(λb.e) a)))) (λe.e) b (λd c e e c a.c)) a)"
-
-cY :: Term
-cY = tRead "λf.(λx.f (x x)) (λx.f (x x))"
-
-cI :: Term
-cI = tRead "λx.x"
-
-cK :: Term
-cK = tRead "λx y.x"
-
-cS :: Term
-cS = tRead "λx y z.x z (y z)"
-
-type VarName = String
-
--- | 
--- >>> print $ Lambda "x" (Var "x")
--- (λx.x)
-
-data Term = Var VarName | Lambda VarName Term | App Term Term deriving (Eq)
+-- >>> import Lambda.Parser.Fancy
+-- >>> import Test.Term
+-- >>> import Test.QuickCheck

 
 varnames :: [VarName]
 varnames = map (:[]) ['a'..'z'] ++ [c : s | s <- varnames, c <- ['a'..'z']]
 
 alphaNorm :: Term -> Term
 
 varnames :: [VarName]
 varnames = map (:[]) ['a'..'z'] ++ [c : s | s <- varnames, c <- ['a'..'z']]
 
 alphaNorm :: Term -> Term

-alphaNorm t = alpha varnames t
+alphaNorm = alpha varnames

   where
   where

-    alpha (v:vs) (Lambda x t) = Lambda v . alpha vs $ substitute x (Var v) t
+    alpha (v:vs) (Lambda x r) = Lambda v . alpha vs $ substitute x (Var v) r

     alpha vs (App u v) = App (alpha vs u) (alpha vs v)
     alpha vs (App u v) = App (alpha vs u) (alpha vs v)

-    alpha vs (Var x) = Var x
-
-pattern RedEx x t s = App (Lambda x t) s
-pattern AppApp a b c = App a (App b c)
-pattern EmLambda x y t = Lambda x (Lambda y t)
-
-
-instance Show Term where
-  show (Var x) = x
-  show (EmLambda x y t) = show (Lambda (x ++ " " ++ y) t)
-  show (Lambda x t) = "(λ" ++ x ++ "." ++ show t ++ ")"
-  show (AppApp a b c) = show a ++ " " ++ braced (App b c)
-  show (App t r) = show t ++ " " ++ show r
-
-braced :: Term -> String
-braced t = "(" ++ show t ++ ")"
-
--- |
--- prop> t == tRead (show (t :: Term))
-
-tRead :: String -> Term
-tRead s = case parseOnly (parseTerm <* endOfInput) (T.pack s) of
-    (Right t) -> t
-    (Left e) -> error e
-
-parseVar :: Parser Term
-parseVar = do
-  x <- many1 (letter <|> digit)
-  return $! Var x
-
-parseLambda :: Parser Term
-parseLambda = do
-  char '\\' <|> char 'λ'
-  vars <- sepBy1 parseVar (char ' ')
-  char '.'
-  t <- parseTerm
-  return $! createLambda vars t
-
-createLambda :: [Term] -> Term -> Term
-createLambda (Var x : vs) t = Lambda x $ createLambda vs t
-createLambda [] t = t
-createLambda _ _ = error "createLambda failed"
-
-parseApp :: Parser Term
-parseApp = do
-  aps <- sepBy1 (parseBraces <|> parseLambda <|> parseVar) (char ' ')
-  return $! createApp aps
-
-createApp :: [Term] -> Term
-createApp [t] = t
-createApp (t:ts:tss) = createApp (App t ts : tss)
-createApp [] = error "empty createApp"
-
-parseBraces :: Parser Term
-parseBraces = do
-  char '('
-  t <- parseTerm
-  char ')'
-  return t 
-
-parseTerm :: Parser Term
-parseTerm = parseApp <|>
-            parseBraces <|>
-            parseLambda <|>
-            parseVar
-
--------------------------------------------------
+    alpha _ (Var x) = Var x
+    alpha [] _ = undefined

 
 isFreeIn :: VarName -> Term -> Bool
 isFreeIn x (Var v) = x == v
 
 isFreeIn :: VarName -> Term -> Bool
 isFreeIn x (Var v) = x == v


@@ -176,7 +77,7 @@ data Strategy = Eager | Lazy
 
 reduceStep :: (Monad m) => Term -> m Term
 reduceStep (RedEx x s t) = return $ substitute x t s
 
 reduceStep :: (Monad m) => Term -> m Term
 reduceStep (RedEx x s t) = return $ substitute x t s

-reduceStep t = return $ t
+reduceStep t = return 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


@@ -198,9 +99,9 @@ unmove x = x
 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 

-    tr f (t@(RedEx _ _ _), c, Up) = do
+    tr f (t@RedEx{}, c, Up) = do

       nt <- f t
       nt <- f t

-      tr f $ (nt, c, Down)
+      tr f (nt, c, Down)

     tr _ (t, E, Up) = return t
     tr f (t, c, Up) = tr f $ move (t, c, Up)
     tr f (t, c, Down) = tr f $ move (t, c, Down)
     tr _ (t, E, Up) = return t
     tr f (t, c, Up) = tr f $ move (t, c, Up)
     tr f (t, c, Down) = tr f $ move (t, c, Down)


@@ -208,18 +109,13 @@ travPost fnc term = tr fnc (term, E, Down)
 travPre :: (Monad m) => (Term -> m Term) -> Term -> m Term
 travPre fnc term = tr fnc (term, E, Down)
   where 
 travPre :: (Monad m) => (Term -> m Term) -> Term -> m Term
 travPre fnc term = tr fnc (term, E, Down)
   where 

-    tr f (t@(RedEx _ _ _), c, Down) = do
+    tr f (t@RedEx{}, c, Down) = do

       nt <- f t
       tr f $ unmove (nt, c, Down)
     tr _ (t, E, Up) = return t
     tr f (t, c, Up) = tr f $ move (t, c, Up)
     tr f (t, c, Down) = tr f $ move (t, c, Down)
 
       nt <- f t
       tr f $ unmove (nt, c, Down)
     tr _ (t, E, Up) = return t
     tr f (t, c, Up) = tr f $ move (t, c, Up)
     tr f (t, c, Down) = tr f $ move (t, c, Down)
 

-printT :: Term -> IO Term
-printT t = do
-  print t
-  return t
-

 -- |
 --
 -- >>> toNormalForm Eager 100 cI
 -- |
 --
 -- >>> toNormalForm Eager 100 cI


@@ -242,7 +138,7 @@ toNormalForm Eager n = flip evalStateT 0 . travPost (cnt >=> short n >=> reduceS
 toNormalForm Lazy  n = flip evalStateT 0 . travPre  (cnt >=> short n >=> reduceStep)
 
 cnt :: (Monad m) => Term -> StateT Int m Term
 toNormalForm Lazy  n = flip evalStateT 0 . travPre  (cnt >=> short n >=> reduceStep)
 
 cnt :: (Monad m) => Term -> StateT Int m Term

-cnt t@(RedEx _ _ _) = do
+cnt t@RedEx{} = do

   modify (+ 1)
   return t
 cnt t = return t
   modify (+ 1)
   return t
 cnt t = return t