concrete-typerep (empty) → 0.1

raw patch · 4 files changed

+125/−0 lines, 4 filesdep +basedep +binarydep +hashablesetup-changed

Dependencies added: base, binary, hashable

Files

• Data/ConcreteTypeRep.hs +77/−0
• LICENSE +30/−0
• Setup.hs +2/−0
• concrete-typerep.cabal +16/−0

@@ -0,0 +1,77 @@+{-# LANGUAGE DeriveDataTypeable, GeneralizedNewtypeDeriving #-}++{- |+This module defines 'Binary' and 'Hashable' instances for 'TypeRep'. These are defined on a newtype of 'TypeRep', namely 'ConcreteTypeRep', for two purposes:++  * to avoid making orphan instances++  * the 'Hashable' instance for 'ConcreteTypeRep' may not be pure enough for some people's tastes.++As usual with 'Typeable', this module will typically be used with some variant of @Data.Dynamic@. Two possible uses of this module are:++  * making hashmaps: @HashMap 'ConcreteTypeRep' Dynamic@++  * serializing @Dynamic@s.++-}++module Data.ConcreteTypeRep (+  ConcreteTypeRep,+  cTypeOf,+  toTypeRep,+  fromTypeRep,+ ) where++import Data.Typeable+import Data.Hashable+import Data.Binary++import System.IO.Unsafe++import Control.Applicative((<$>))++-- | Abstract type providing the functionality of 'TypeRep', but additionally supporting hashing and serialization. +--+-- The 'Eq' instance is just the 'Eq' instance for 'TypeRep', so an analogous guarantee holds: @'cTypeOf' a == 'cTypeOf' b@ if and only if @a@ and @b@ have the same type.+-- The hashing and serialization functions preserve this equality.+newtype ConcreteTypeRep = CTR { unCTR :: TypeRep } deriving(Eq, Typeable)++-- | \"Concrete\" version of 'typeOf'.+cTypeOf :: Typeable a => a -> ConcreteTypeRep+cTypeOf = fromTypeRep . typeOf++-- | Converts to the underlying 'TypeRep'+toTypeRep :: ConcreteTypeRep -> TypeRep+toTypeRep = unCTR++-- | Converts from the underlying 'TypeRep'+fromTypeRep :: TypeRep -> ConcreteTypeRep+fromTypeRep = CTR++-- show as a normal TypeRep+instance Show ConcreteTypeRep where+  showsPrec i = showsPrec i . unCTR++-- | The 'Hashable' instance is defined by running 'unsafePerformIO' on @'typeRepKey' :: 'TypeRep' -> IO Int@. +--+-- This instance actually provides a stronger guarantee than required: it is guaranteed that @t1 == t2@ if and only if @'hash' t1 == 'hash' t2@.+--+-- As the documentation for 'typeRepKey' notes, \"... the actual value of the key may vary from run to run of the program. You should only rely on the equality property, not any actual key value. The relative ordering of keys has no meaning either.\"+instance Hashable ConcreteTypeRep where+  hash = unsafePerformIO . typeRepKey . toTypeRep++------------- serialization: this uses Gökhan San's construction, from+---- http://www.mail-archive.com/haskell-cafe@haskell.org/msg41134.html+newtype SerialRep = SR (String, [SerialRep]) deriving(Binary)++toSerial :: ConcreteTypeRep -> SerialRep+toSerial (CTR t) = +  case splitTyConApp t of+    (con, args) -> SR (tyConString con, map (toSerial . CTR) args)++fromSerial :: SerialRep -> ConcreteTypeRep+fromSerial (SR (con, args)) = CTR $ mkTyConApp (mkTyCon con) (map (unCTR . fromSerial) args)++instance Binary ConcreteTypeRep where+  put = put . toSerial+  get = fromSerial <$> get

@@ -0,0 +1,30 @@+Copyright (c)2011, Reiner Pope++All rights reserved.++Redistribution and use in source and binary forms, with or without+modification, are permitted provided that the following conditions are met:++    * Redistributions of source code must retain the above copyright+      notice, this list of conditions and the following disclaimer.++    * Redistributions in binary form must reproduce the above+      copyright notice, this list of conditions and the following+      disclaimer in the documentation and/or other materials provided+      with the distribution.++    * Neither the name of Reiner Pope nor the names of other+      contributors may be used to endorse or promote products derived+      from this software without specific prior written permission.++THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

@@ -0,0 +1,2 @@+import Distribution.Simple+main = defaultMain

@@ -0,0 +1,16 @@+Name:                concrete-typerep+Version:             0.1+Synopsis:            Binary and Hashable instances for TypeRep+Description:         Binary and Hashable instances for TypeRep+License:             BSD3+License-file:        LICENSE+Author:              Reiner Pope+Maintainer:          reiner.pope@gmail.com+Category:            Data+Build-type:          Simple+Cabal-version:       >=1.2++Library+  Exposed-modules:     Data.ConcreteTypeRep++  Build-depends:       base < 5, binary, hashable