diff --git a/fast/Data/Reflection.hs b/fast/Data/Reflection.hs --- a/fast/Data/Reflection.hs +++ b/fast/Data/Reflection.hs @@ -1,4 +1,6 @@ -{-# LANGUAGE MultiParamTypeClasses, FunctionalDependencies, Rank2Types #-} +{-# LANGUAGE MultiParamTypeClasses #-} +{-# LANGUAGE FunctionalDependencies #-} +{-# LANGUAGE Rank2Types #-} ---------------------------------------------------------------------------- -- | -- Module : Data.Reflection @@ -11,8 +13,9 @@ -- Stability : experimental -- Portability : non-portable -- --- Based on the Functional Pearl: Implicit Configurations paper by --- Oleg Kiselyov and Chung-chieh Shan. +-- Reifies arbitrary terms at the type level. Based on the Functional +-- Pearl: Implicit Configurations paper by Oleg Kiselyov and +-- Chung-chieh Shan. -- -- -- @@ -20,19 +23,18 @@ -- and to cheat by using knowledge of GHC's internal representations -- by Edward Kmett and Elliott Hird. -- --- Usage reduces to using two combinators, 'reify' and 'reflect'. +-- Usage comes down to two combinators, 'reify' and 'reflect'. -- --- > ghci> reify 6 (\p -> reflect p + reflect p) :: Int --- > 12 +-- >>> reify 6 (\p -> reflect p + reflect p) +-- 12 -- --- The argument passed along by reify is just a @data Proxy t = +-- The argument passed along by reify is just a @data 'Proxy' t = -- Proxy@, so all of the information needed to reconstruct your value -- has been moved to the type level. This enables it to be used when -- constructing instances (see @examples/Monoid.hs@). ------------------------------------------------------------------------------- module Data.Reflection ( - -- * Reifying any term at the type level Reifies(..) , reify ) where @@ -41,10 +43,12 @@ import Unsafe.Coerce class Reifies s a | s -> a where - reflect :: p s -> a + -- | Recover a value inside a 'reify' context, given a proxy for its + -- reified type. + reflect :: proxy s -> a -newtype Magic a w = Magic (forall s. Reifies s a => Proxy s -> w) +newtype Magic a r = Magic (forall s. Reifies s a => Proxy s -> r) -reify :: a -> (forall s. Reifies s a => Proxy s -> w) -> w +-- | Reify a value at the type level, to be recovered with 'reflect'. +reify :: a -> (forall s. Reifies s a => Proxy s -> r) -> r reify a k = (unsafeCoerce (Magic k) $! const a) Proxy - diff --git a/reflection.cabal b/reflection.cabal --- a/reflection.cabal +++ b/reflection.cabal @@ -1,5 +1,5 @@ name: reflection -version: 1.1.2 +version: 1.1.3 license: BSD3 license-file: LICENSE author: Edward A. Kmett, Elliott Hird, Oleg Kiselyov and Chung-chieh Shan @@ -7,7 +7,8 @@ stability: experimental homepage: http://github.com/ekmett/reflection category: Data, Reflection, Dependent Types -synopsis: Reifies arbitrary terms into types that can be reflected back into terms +synopsis: Reifies arbitrary terms into types that can be reflected back + into terms copyright: 2009-2012 Edward A. Kmett, 2012 Elliott Hird, 2004 Oleg Kiselyov and Chung-chieh Shan @@ -18,16 +19,19 @@ \"Functional Pearl: Implicit Configurations\" by Oleg Kiselyov and Chung-chieh Shan. However, the API has been streamlined to improve performance. . - The original paper can be obtained from + The original paper can be obtained from + . . /Changes from 0.5 to 1.1/: . - * Much faster implementation available that is about 50 /times/ faster than 0.9 and which runs - purely on black magic. This version is now used by default. To turn it off install with the - 'slow' flag. If you encounter a problem with implementation, please contact the author. + * Much faster implementation available that is about 50 /times/ faster than + 0.9 and which runs purely on black magic. This version is now used by + default. To turn it off install with the @slow@ flag. If you encounter a + problem with the implementation, please contact the author. . - * Removed @ReifiedNum@, @reflectNum@, and @reifyIntegral@; @reify@ and @reflect@ are - about 3 orders of magnitude faster than the special case combinators were. + * Removed @ReifiedNum@, @reflectNum@, and @reifyIntegral@; @reify@ and + @reflect@ are about 3 orders of magnitude faster than the special case + combinators were. . /Changes in 0.5/: . @@ -60,6 +64,9 @@ library ghc-options: -Wall + if impl(ghc >= 7.2) + default-extensions: Trustworthy + build-depends: base >= 4 && < 5, tagged >= 0.2.3 && < 0.3 @@ -69,10 +76,9 @@ if impl(ghc) && !flag(slow) hs-source-dirs: fast else - other-extensions: ScopedTypeVariables, FlexibleInstances + other-extensions: ScopedTypeVariables, FlexibleInstances, CPP hs-source-dirs: slow other-extensions: MultiParamTypeClasses, FunctionalDependencies, Rank2Types exposed-modules: Data.Reflection - diff --git a/slow/Data/Reflection.hs b/slow/Data/Reflection.hs --- a/slow/Data/Reflection.hs +++ b/slow/Data/Reflection.hs @@ -1,9 +1,13 @@ -{-# LANGUAGE FunctionalDependencies #-} +{-# LANGUAGE CPP #-} {-# LANGUAGE MultiParamTypeClasses #-} +{-# LANGUAGE FunctionalDependencies #-} {-# LANGUAGE ScopedTypeVariables #-} {-# LANGUAGE FlexibleInstances #-} {-# LANGUAGE Rank2Types #-} -{-# OPTIONS_GHC -fno-cse -fno-full-laziness -fno-float-in -fno-warn-unused-binds #-} +{-# OPTIONS_GHC -fno-cse #-} +{-# OPTIONS_GHC -fno-full-laziness #-} +{-# OPTIONS_GHC -fno-float-in #-} +{-# OPTIONS_GHC -fno-warn-unused-binds #-} ---------------------------------------------------------------------------- -- | -- Module : Data.Reflection @@ -16,20 +20,21 @@ -- Stability : experimental -- Portability : non-portable -- --- Based on the Functional Pearl: Implicit Configurations paper by --- Oleg Kiselyov and Chung-chieh Shan. +-- Reifies arbitrary terms at the type level. Based on the Functional +-- Pearl: Implicit Configurations paper by Oleg Kiselyov and +-- Chung-chieh Shan. -- -- -- --- The approach from the paper was modified to work with Data.Proxy and streamline --- the API by Edward Kmett and Elliott Hird. +-- The approach from the paper was modified to work with Data.Proxy +-- and streamline the API by Edward Kmett and Elliott Hird. -- --- Usage reduces to using two combinators, 'reify' and 'reflect'. +-- Usage comes down to two combinators, 'reify' and 'reflect'. -- --- > ghci> reify 6 (\p -> reflect p + reflect p) :: Int --- > 12 +-- >>> reify 6 (\p -> reflect p + reflect p) +-- 12 -- --- The argument passed along by reify is just a @data Proxy t = +-- The argument passed along by reify is just a @data 'Proxy' t = -- Proxy@, so all of the information needed to reconstruct your value -- has been moved to the type level. This enables it to be used when -- constructing instances (see @examples/Monoid.hs@). @@ -37,7 +42,6 @@ module Data.Reflection ( - -- * Reifying any term at the type level Reifies(..) , reify ) where @@ -51,7 +55,7 @@ import Data.Word class B s where - reflectByte :: p s -> IntPtr + reflectByte :: proxy s -> IntPtr #define CAT(a,b) a/**/b @@ -95,7 +99,7 @@ impossible :: a impossible = error "Data.Reflection.reifyByte: impossible" -reifyByte :: Word8 -> (forall s. B s => Proxy s -> w) -> w +reifyByte :: Word8 -> (forall s. B s => Proxy s -> r) -> r reifyByte w k = case w of { #define GO(n) n -> k (Proxy :: Proxy CAT(T,n)); BYTES(GO) @@ -104,7 +108,9 @@ } class Reifies s a | s -> a where - reflect :: p s -> a + -- | Recover a value inside a 'reify' context, given a proxy for its + -- reified type. + reflect :: proxy s -> a newtype Stable b0 b1 b2 b3 b4 b5 b6 b7 a = Stable (Stable b0 b1 b2 b3 b4 b5 b6 b7 a) @@ -142,7 +148,8 @@ reflectBefore f = const $! f Proxy {-# NOINLINE reflectBefore #-} -reify :: a -> (forall s. (Reifies s a) => Proxy s -> w) -> w +-- | Reify a value at the type level, to be recovered with 'reflect'. +reify :: a -> (forall s. (Reifies s a) => Proxy s -> r) -> r reify a k = unsafeDupablePerformIO $ do p <- newStablePtr a let n = stablePtrToIntPtr p