Extract UnifyT into its own package and get an example going
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@ -106,3 +106,7 @@ in upstream
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with logict.repo = "https://dev.danilafe.com/Everything-I-Know-About-Types/logict.git"
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with logict.version = "24298710fa940bfcf2d272bc6d5c7417f2bfccfe"
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with logict.dependencies = [ "control", "lists", "maybe", "prelude", "transformers", "tuples" ]
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with unifyt.repo = "https://dev.danilafe.com/Everything-I-Know-About-Types/unifyt.git"
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with unifyt.version = "d1e227dbed5e5af63510872b95a9417200c0d7c7"
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with unifyt.dependencies = [ "control", "foldable-traversable", "lazy", "maybe", "newtype", "ordered-collections", "prelude", "transformers", "tuples" ]
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@ -24,6 +24,7 @@ to generate this file without the comments in this block.
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, "prelude"
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, "transformers"
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, "tuples"
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, "unifyt"
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]
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, packages = ./packages.dhall
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, sources = [ "src/**/*.purs", "test/**/*.purs" ]
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@ -13,6 +13,9 @@ import Control.Applicative (class Applicative, pure)
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import Control.Bind (class Bind, bind, (>>=))
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import Control.MonadPlus (class MonadPlus)
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import Control.Monad.Logic.Class (class MonadLogic, msplit, interleave)
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import Control.Monad.Unify.Class (class MonadUnify, class Unifiable, class UnificationVariable, Stream(..), squash, alongside, ComparisonAction(..))
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import Control.Monad.Unify.Trans (UnifyT(..), runUnifyT)
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import Control.Monad.Logic.Trans (SFKT(..), runSFKT)
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import Data.List (List(..), (:))
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import Data.Functor (class Functor, (<$>), map)
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import Data.Eq (class Eq)
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@ -53,14 +56,6 @@ instance Traversable Expr where
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traverse f e = sequence (f <$> e)
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data Stream k = StreamCons k (Lazy (Stream k))
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pop :: forall k. Stream k -> Tuple k (Stream k)
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pop (StreamCons k lks) = Tuple k (force lks)
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class Ord k <= UnificationVariable k where
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variables :: Stream k
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newtype IntVar = MkIntVar Int
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derive instance Eq IntVar
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@ -70,16 +65,6 @@ instance UnificationVariable IntVar where
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variables = mkVarList 0
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where mkVarList n = StreamCons (MkIntVar n) $ defer $ \_ -> mkVarList (n+1)
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data ComparisonAction k f
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= Merge k k
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| Store k (f k)
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| Fail
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class (UnificationVariable k, Traversable f) <= Unifiable k f where
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variable :: k -> f k
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squash :: f (f k) -> f k
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alongside :: f k -> f k -> f (ComparisonAction k f)
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instance UnificationVariable k => Unifiable k Expr where
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variable = Var
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squash (Var f) = f
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@ -95,93 +80,22 @@ instance UnificationVariable k => Unifiable k Expr where
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combine Nil (_:_) = (Var Fail) : Nil
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combine (x:xs) (y:ys) = alongside x y : combine xs ys
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class (Unifiable k f, MonadPlus m) <= MonadUnify k f m | m -> k, m -> f where
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fresh :: m k
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merge :: k -> k -> m Unit
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store :: k -> f k -> m Unit
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reify :: f k -> m (f k)
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newtype Unifier a = MkUnifier (UnifyT IntVar Expr (SFKT Maybe) a)
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unify :: forall k f m. MonadUnify k f m => f k -> f k -> m Unit
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unify f1 f2 =
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do
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_ <- traverse process $ alongside f1 f2
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pure unit
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where
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process (Merge k1 k2) = merge k1 k2
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process (Store k f) = store k f
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process Fail = empty
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derive instance Newtype (Unifier a) _
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derive newtype instance Functor Unifier
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derive newtype instance Apply Unifier
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derive newtype instance Applicative Unifier
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derive newtype instance Alternative Unifier
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derive newtype instance Bind Unifier
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derive newtype instance Monad Unifier
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derive newtype instance MonadPlus Unifier
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derive newtype instance MonadUnify IntVar Expr Unifier
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type UnificationState k f =
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{ boundVariables :: Map k { equivalence :: Set k, boundTo :: Maybe (f k) }
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, currentVariables :: Stream k
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}
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-- >:(
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instance MonadLogic Unifier where
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msplit m = MkUnifier $ MkUnifyT $ map (map (rmap (MkUnifier <<< MkUnifyT))) $ msplit $ un MkUnifyT $ un MkUnifier m
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interleave = over2 MkUnifier (over2 MkUnifyT interleave)
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newtype UnifyT k f m a = MkUnifyT (StateT (UnificationState k f) m a)
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derive instance Newtype (UnifyT k f m a) _
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derive instance Functor m => Functor (UnifyT k f m)
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instance Monad m => Apply (UnifyT k f m) where
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apply m1 m2 = MkUnifyT $ apply (un MkUnifyT m1) (un MkUnifyT m2)
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instance Monad m => Applicative (UnifyT k f m) where
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pure a = MkUnifyT $ pure a
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instance Monad m => Bind (UnifyT k f m) where
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bind m f = MkUnifyT $ (un MkUnifyT m) >>= (un MkUnifyT <<< f)
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instance Monad m => Monad (UnifyT k f m)
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instance (Monad m, Alt m) => Alt (UnifyT k f m) where
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alt = over2 MkUnifyT alt
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instance (Monad m, Plus m) => Plus (UnifyT k f m) where
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empty = MkUnifyT empty
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instance (Monad m, Alternative m) => Alternative (UnifyT k f m)
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instance (MonadPlus m) => MonadPlus (UnifyT k f m)
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instance MonadLogic m => MonadLogic (UnifyT k f m) where
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msplit m = MkUnifyT $ map (map (rmap MkUnifyT)) $ msplit $ un MkUnifyT m
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interleave m1 m2 = over2 MkUnifyT interleave m1 m2
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instance (Unifiable k f, MonadPlus m) => MonadUnify k f (UnifyT k f m) where
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fresh = MkUnifyT $ do
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Tuple k restVariables <- gets (pop <<< _.currentVariables)
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_ <- modify $ _ { currentVariables = restVariables }
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pure k
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merge k1 k2 = do
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boundVariables <- MkUnifyT $ gets _.boundVariables
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let
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equivalence k = fromMaybe (singleton k) (_.equivalence <$> lookup k boundVariables)
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boundTo k = lookup k boundVariables >>= _.boundTo
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fullSet = equivalence k1 `union` equivalence k2
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newTerm <-
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case boundTo k1 /\ boundTo k2 of
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Just t1 /\ Just t2 -> unify t1 t2 >>= const (Just <$> reify t1)
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Just t1 /\ Nothing -> pure $ Just t1
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Nothing /\ Just t2 -> pure $ Just t2
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Nothing /\ Nothing -> pure $ Nothing
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let newMapValue = {equivalence: fullSet, boundTo: newTerm}
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_ <- MkUnifyT $ modify $ _ { boundVariables = foldr (flip insert newMapValue) boundVariables fullSet }
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pure unit
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store k f = do
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boundVariables <- MkUnifyT $ gets _.boundVariables
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let fullSet = fromMaybe (singleton k) (_.equivalence <$> lookup k boundVariables)
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let anyBound = any (isJust <<< (_>>=(_.boundTo)) <<< (flip lookup boundVariables)) fullSet
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if anyBound
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then empty
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else do
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let newMapValue = {equivalence: fullSet, boundTo: Just f}
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_ <- MkUnifyT $ modify $ _ { boundVariables = foldr (flip insert newMapValue) boundVariables fullSet }
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pure unit
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reify f =
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MkUnifyT $ do
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boundVariables <- gets _.boundVariables
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let
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reify' f' = squash $ process <$> f'
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process k = fromMaybe (variable k) (reify' <$> (lookup k boundVariables >>= _.boundTo))
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pure $ reify' f
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runUnifyT :: forall k f m a. Monad m => UnificationVariable k => UnifyT k f m a -> m a
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runUnifyT m = fst <$> runStateT (un MkUnifyT m) { boundVariables: Map.empty, currentVariables: variables }
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runUnifier :: forall a. Unifier a -> Maybe a
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runUnifier m = runSFKT (runUnifyT $ un MkUnifier m) (const <<< Just) Nothing
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@ -1,6 +1,23 @@
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module Test.Main where
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import Prelude
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import Language.Bergamot.Syntax
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import Control.Monad.Logic.Trans
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import Control.Monad.Logic.Class
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import Control.Monad.Unify.Trans
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import Control.Monad.Unify.Class
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import Data.List
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import Data.Maybe
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main :: Unit
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main = unit
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runSomeComputation :: forall m. MonadLogic m => MonadUnify IntVar Expr m => m (Expr IntVar)
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runSomeComputation = do
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x1 <- fresh
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x2 <- fresh
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let binPred = Atom "hello" $ fromFoldable [variable x1, variable x2]
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let realBinPred = Atom "hello" $ fromFoldable [Atom "first" $ fromFoldable [], Atom "second" $ fromFoldable []]
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unify binPred realBinPred
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(unify (variable x1) (variable x2) >>= const (reify (variable x1))) `interleave` (unify (variable x1) (variable x1) >>= const (reify (variable x2)))
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main :: Maybe (Expr IntVar)
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main = runUnifier runSomeComputation
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