strict-identity: Strict Identity Monad, handy for writing fast code!

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strict Identity monad for writing strict performant code sanely


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Versions 0.1.0.0, 0.1.0.0
Change log changelog.md
Dependencies base (>=4.3 && <4.8) [details]
License BSD-3-Clause
Author Carter Tazio Schonwald
Maintainer carter at wellposed.com
Category Control
Home page https://github.com/cartazio/strict-identity
Source repo head: git clone http://github.com/cartazio/strict-identity.git
Uploaded by CarterSchonwald at 2014-01-12T08:19:45Z

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Readme for strict-identity-0.1.0.0

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#About

strict-identity package is meant to make writing nested strict let expression heavy code a bit more pleasant, for all those High Performance Haskell lib authors out there.

A simple example of the strict identity monad in action (and working wonderfully) is the following bit fiddling code, which generates C competitive assembly on both major GHC backends, -fasm and -fllvm

(>>) = unsafeShiftR
(<<) = unsafeShiftL
outerShuffle64A :: Word -> Word 
outerShuffle64A !x =
    runStrictIdentity $! do
        x <- return $! ((x .&. 0x00000000FFFF0000) << 16 )
            .|. ((x>>16) .&. 0x00000000FFFF0000) .|. (x .&. 0xFFFF00000000FFFF)
        x <-  return $! ((x .&. 0x0000FF000000FF00 ) <<  8 )
            .|. (x >> 8) .&. 0x0000FF000000FF00 .|. (x  .&. 0xFF0000FFFF0000FF)
        x<-  return $! (( x .&. 0x00F000F000F000F0 ) << 4 )
            .|. (x >> 4) .&. 0x00F000F000F000F0 .|. (x .&. 0xF00FF00FF00FF00F )
        x<-   return $!((x .&.  0x0C0C0C0C0C0C0C0C )<< 2 )
            .|. (x >> 2) .&. 0x0C0C0C0C0C0C0C0C .|.( x .&. 0xC3C3C3C3C3C3C3C3)
        x<-   return $! ( (x .&. 0x2222222222222222)  << 1 ) 
            .|. (x>> 1) .&. 0x2222222222222222 .|. (x .&. 0x9999999999999999)
        return x