constraints 0.2 → 0.3

raw patch · 4 files changed

+62/−20 lines, 4 files

Files

• Data/Constraint.hs +14/−0
• Data/Constraint/Forall.hs +16/−2
• Data/Constraint/Unsafe.hs +31/−17
• constraints.cabal +1/−1

@@ -11,7 +11,19 @@ {-# LANGUAGE Trustworthy #-} {-# LANGUAGE Rank2Types #-} {-# LANGUAGE GADTs #-}+-----------------------------------------------------------------------------+-- |+-- Module      :  Data.Constraint+-- Copyright   :  (C) 2011-2012 Edward Kmett,+-- License     :  BSD-style (see the file LICENSE)+--+-- Maintainer  :  Edward Kmett <ekmett@gmail.com>+-- Stability   :  experimental+-- Portability :  non-portable+--+---------------------------------------------------------------------------- + module Data.Constraint   (   -- * Constraints@@ -111,10 +123,12 @@ top :: a :- () top = Sub Dict +-- | Reify the relationship between a class and its superclass constraints as a class class Class b h | h -> b where   cls :: h :- b  infixr 9 :=>+-- | Reify the relationship between an instance head and its body as a class class b :=> h | h -> b where   ins :: b :- h 

@@ -6,6 +6,17 @@ {-# LANGUAGE KindSignatures #-} {-# LANGUAGE TypeOperators #-} {-# LANGUAGE Trustworthy #-}+-----------------------------------------------------------------------------+-- |+-- Module      :  Data.Constraint.Forall+-- Copyright   :  (C) 2011-2012 Edward Kmett,+-- License     :  BSD-style (see the file LICENSE)+--+-- Maintainer  :  Edward Kmett <ekmett@gmail.com>+-- Stability   :  experimental+-- Portability :  non-portable+--+----------------------------------------------------------------------------  module Data.Constraint.Forall   ( Forall, inst@@ -18,14 +29,17 @@ -- skolem variables, do not export! data A data B+-- | A quantified constraint type Forall (p :: * -> Constraint) = (p A, p B)  data F a data M a type Forall1 (p :: (* -> *) -> Constraint) = (p F, p M) +-- | instantiate a quantified constraint on kind @*@ inst :: forall p a. Forall p :- p a-inst = trans (evil :: p A :- p a) weaken1+inst = trans (unsafeCoerceConstraint :: p A :- p a) weaken1 +-- | instantiate a quantified constraint on kind @* -> *@ inst1 :: forall (p :: (* -> *) -> Constraint) (f :: * -> *). Forall1 p :- p f-inst1 = trans (evil :: p F :- p f) weaken1+inst1 = trans (unsafeCoerceConstraint :: p F :- p f) weaken1

@@ -7,14 +7,24 @@ {-# LANGUAGE TypeOperators #-} {-# LANGUAGE Rank2Types #-} {-# LANGUAGE GADTs #-}-+-----------------------------------------------------------------------------+-- |+-- Module      :  Data.Constraint.Unsafe+-- Copyright   :  (C) 2011-2012 Edward Kmett+-- License     :  BSD-style (see the file LICENSE)+--+-- Maintainer  :  Edward Kmett <ekmett@gmail.com>+-- Stability   :  experimental+-- Portability :  non-portable+--+---------------------------------------------------------------------------- module Data.Constraint.Unsafe-  ( evil-  , derive-  , underive+  ( unsafeCoerceConstraint+  , unsafeDerive+  , unsafeUnderive   -- * Sugar-  , applicative-  , alternative+  , unsafeApplicative+  , unsafeAlternative   ) where  import Control.Applicative@@ -23,18 +33,22 @@ import Data.Constraint import Unsafe.Coerce -evil :: a :- b-evil = unsafeCoerce refl--derive :: Newtype n o => (o -> n) -> t o :- t n-derive _ = evil+-- | Coerce a dictionary unsafely from one type to another+unsafeCoerceConstraint :: a :- b+unsafeCoerceConstraint = unsafeCoerce refl -underive :: Newtype n o => (o -> n) -> t n :- t o-underive _ = evil+-- | Coerce a dictionary unsafely from one type to a newtype of that type+unsafeDerive :: Newtype n o => (o -> n) -> t o :- t n+unsafeDerive _ = unsafeCoerceConstraint -applicative :: forall m a. Monad m => (Applicative m => m a) -> m a-applicative m = m \\ trans (evil :: Applicative (WrappedMonad m) :- Applicative m) ins+-- | Coerce a dictionary unsafely from a newtype of a type to the base type+unsafeUnderive :: Newtype n o => (o -> n) -> t n :- t o+unsafeUnderive _ = unsafeCoerceConstraint -alternative :: forall m a. MonadPlus m => (Alternative m => m a) -> m a-alternative m = m \\ trans (evil :: Alternative (WrappedMonad m) :- Alternative m) ins+-- | Construct an Applicative instance from a Monad+unsafeApplicative :: forall m a. Monad m => (Applicative m => m a) -> m a+unsafeApplicative m = m \\ trans (unsafeCoerceConstraint :: Applicative (WrappedMonad m) :- Applicative m) ins +-- | Construct an Alternative instance from a MonadPlus+unsafeAlternative :: forall m a. MonadPlus m => (Alternative m => m a) -> m a+unsafeAlternative m = m \\ trans (unsafeCoerceConstraint :: Alternative (WrappedMonad m) :- Alternative m) ins

@@ -1,6 +1,6 @@ name:          constraints category:      Constraints-version:       0.2+version:       0.3 license:       BSD3 cabal-version: >= 1.10 license-file:  LICENSE