🔥 Data.Amb.

semantic-diff.cabal

@@ -17,7 +17,6 @@ library
                      , Alignment
                      , Category
                      , Data.Align.Generic
-                     , Data.Amb
                      , Data.Blob
                      , Data.Functor.Both
                      , Data.Functor.Classes.Eq.Generic

src/Data/Amb.hs

@@ -1,48 +0,0 @@
-{-# LANGUAGE MultiParamTypeClasses, NoStrictData #-}
-module Data.Amb where
-
-import Control.Monad.Error.Class
-import Data.Bifunctor
-import Data.List.NonEmpty
-import Data.Semigroup
-
--- | The ambiguity monad, the result of nondeterministic choice.
---
---   Values are either the empty set (with an error value indicating why), or a 'NonEmpty' list of ambiguous results.
-data Amb l r
-  = None l            -- ^ No results; an error.
-  | Some (NonEmpty r) -- ^ One or more results.
-  deriving (Eq, Foldable, Functor, Show, Traversable)
-
--- | Disambiguate an 'Amb' by case analysis.
---
---   If the value is @'None' l@, apply the first function to @l@; if it is @'Some' rs@, apply the second function to @rs@.
-disamb :: (l -> a) -> (NonEmpty r -> a) -> Amb l r -> a
-disamb f _ (None l) = f l
-disamb _ g (Some r) = g r
-
-
-instance Bifunctor Amb where
-  bimap f _ (None l) = None (f l)
-  bimap _ g (Some r) = Some (fmap g r)
-
-instance Semigroup (Amb l r) where
-  l <> None _ = l
-  None _ <> r = r
-  Some as <> Some bs = Some (as <> bs)
-
-instance Applicative (Amb l) where
-  pure a = Some (a :| [])
-  None l <*> _ = None l
-  _ <*> None r = None r
-  Some fs <*> Some as = Some (fs <*> as)
-
-instance Monad (Amb l) where
-  return = pure
-  None a >>= _ = None a
-  Some as >>= f = sconcat (f <$> as)
-
-instance MonadError l (Amb l) where
-  throwError = None
-  None a  `catchError` f = f a
-  Some as `catchError` _ = Some as