nf (empty) → 1.0.0.0

raw patch · 5 files changed

+140/−0 lines, 5 filesdep +basedep +deepseqsetup-changed

Dependencies added: base, deepseq

Files

• Data/NF.hs +52/−0
• Data/NF/Internal.hs +34/−0
• LICENSE +30/−0
• Setup.hs +2/−0
• nf.cabal +22/−0

@@ -0,0 +1,52 @@+{-# LANGUAGE CPP #-}+#if __GLASGOW_HASKELL__ >= 702+{-# LANGUAGE Safe #-}+#endif+-----------------------------------------------------------------------------+-- |+-- Module      :  Data.NF+-- Copyright   :  (c) Stanford University 2015+-- License     :  BSD-style (see the file LICENSE)+--+-- Maintainer  :  ezyang@cs.stanford.edu+-- Stability   :  experimental+-- Portability :  portable+--+-- This module provides a data type, 'NF', representing data which has+-- been evaluated to \"Normal Form\".  This is a useful type discipline+-- for many situations when normal form data is necessary, e.g. when+-- transmitting data to other threads over channels.  If a library+-- that you are using has the following type:+--+-- @+-- strictWriteChan :: 'NFData' a => 'Control.Concurrent.Chan' a -> a -> 'IO' ()+-- @+--+-- you can specialize it to the following type in order to avoid the+-- cost of repeatedly 'deepseq'ing a value when it is not necessary:+--+-- @+-- strictWriteChan_ :: 'Control.Concurrent.Chan' ('NF' a) -> 'NF' a -> 'IO' ()+-- strictWriteChan_ = strictWriteChan+-- @+--+-- You should also consider providing APIs which only accept 'NF'+-- values, to prevent users from accidentally 'deepseq'ing.+module Data.NF (+    NF,+    makeNF, getNF,+  ) where++import Control.DeepSeq+import Data.NF.Internal++-- | Creates a value of type 'NF'.  The first time the result is+-- evaluated to whnf, the value will be 'rnf'ed.  To avoid this+-- 'rnf', see 'UnsafeNF'.+makeNF :: NFData a => a -> NF a+makeNF x = x `deepseq` UnsafeNF x++-- | Retrieves @a@ from a value of type @'NF' a@; this value+-- is guaranteed to be in normal form.+getNF :: NF a -> a+getNF (UnsafeNF a) = a

@@ -0,0 +1,34 @@+{-# LANGUAGE CPP #-}+#if __GLASGOW_HASKELL__ >= 702+{-# LANGUAGE Safe #-}+#endif+-----------------------------------------------------------------------------+-- |+-- Module      :  Data.NF.Internal+-- Copyright   :  (c) Stanford University 2015+-- License     :  BSD-style (see the file LICENSE)+--+-- Maintainer  :  ezyang@cs.stanford.edu+-- Stability   :  experimental+-- Portability :  portable+--+-- This module provides the constructor for the type 'NF', allowing+-- you to create values of type 'NF' without any runtime overhead+-- if you fulfill a proof obligation that the value is already in+-- normal form.+module Data.NF.Internal(NF(..)) where++import Control.DeepSeq++-- | 'NF' is an abstract data type representing data which has been+-- evaluated to normal form.  Specifically, if a value of type @'NF' a@+-- is in weak head normal form, then it is in reduced normal form;+-- alternatively, it is only necessary to 'seq' an @'NF' a@ to assure that+-- it is fully evaluated.+newtype NF a+    -- | For @'UnsafeNF' x@ to preserve the 'NF' invariant, you must+    -- show that @'UnsafeNF' x == 'deepseq' x ('UnsafeNF' x)@.+    = UnsafeNF a++instance NFData (NF a) where+    rnf x = x `seq` ()

@@ -0,0 +1,30 @@+Copyright (c) 2015, Edward Z. Yang++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 Edward Z. Yang 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 +1,22 @@+name:                nf+version:             1.0.0.0+synopsis:            NF data type to statically enforce normal form +description:         This package provides a data type NF representing+                     data which has been evaluated to normal form.  This+                     is a useful type discipline for many situations when+                     normal form data is necessary, e.g. when transmitting+                     data to other threads over channels.+homepage:            https://github.com/ezyang/nf+license:             BSD3+license-file:        LICENSE+author:              Edward Z. Yang+maintainer:          ezyang@cs.stanford.edu+category:            Data+build-type:          Simple+cabal-version:       >=1.10++library+  exposed-modules:     Data.NF, Data.NF.Internal+  other-extensions:    Safe, CPP+  build-depends:       base >= 2 && <= 4, deepseq+  default-language:    Haskell2010