Defining a type depending on the word size of platform
Hi guys! I'm working on a random generator package and want to ask, whether it's possible to generate a type like Int, that can have different sizes at runtime. Motivation: The package ships to generators, one for 32 (lets name it MyGen32) and one for 64 bits (MyGen64). As it is not good for performance to use the wrong one, I also want to provide a type MyGen, that is either a type synonym for MyGen32 or MyGen64, depending on the platform. Any ideas how to do this at compile time? I want this to compile with Cabal so that anybody can download it as a package. I guess the easiest way would be to use CPP, but is there any flag for the wordsize? Yours, Robert Clausecker
On Sunday 02 January 2011 13:45:13, Robert Clausecker wrote:
I guess the easiest way would be to use CPP, but is there any flag for the wordsize?
Not directly, but I think {-# LANGUAGE CPP #-} #include "MachDeps.h" #if WORD_SIZE_IN_BITS == 32 type MyGen = MyGen32 #else // GHC only works with 32- and 64-bit words type MyGen = MyGen64 #endif should do it. MachDeps.h ties you to GHC of course, if you want it to work on other compilers too, I guess you need a configure script.
Hi, maybe you have already considered this and dropped it out for whenever reasons. Anyways, what if you stick with Int or Data.Word.Word types and use Data.Bits.bitSize or maxBound to check in runtime what the word size is. It might be easier than using CPP extension. ~dsouza On Sun, Jan 2, 2011 at 11:16 AM, Daniel Fischer < daniel.is.fischer@googlemail.com> wrote:
On Sunday 02 January 2011 13:45:13, Robert Clausecker wrote:
I guess the easiest way would be to use CPP, but is there any flag for the wordsize?
Not directly, but I think
{-# LANGUAGE CPP #-}
#include "MachDeps.h"
#if WORD_SIZE_IN_BITS == 32
type MyGen = MyGen32
#else // GHC only works with 32- and 64-bit words
type MyGen = MyGen64
#endif
should do it.
MachDeps.h ties you to GHC of course, if you want it to work on other compilers too, I guess you need a configure script.
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participants (3)
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Daniel Fischer -
Diego Souza -
Robert Clausecker