[Haskell] sizeFM type

Remi Turk rturk at science.uva.nl
Mon Apr 26 22:21:09 EDT 2004

On Mon, Apr 26, 2004 at 08:58:53PM +0200, Wolfgang Jeltsch wrote:
> Am Montag, 26. April 2004 20:45 schrieb Don Groves:
> > Some languages handle the Int/Integer question automatically,
> > determined by the size of the integer in question.  Int is used
> > until the integer excedes what the underlying architecture can
> > handle, then the switch is made to Integer (bignum).  Is this
> > something that could be handled similarly by the Haskell compiler
> > without violating anything?  Just thinking out loud...
> But you can have a type which uses a "small int" representation for small 
> numbers and a "big int" representation for big numbers.  This is probably 
> what you mean, and this is AFAIK exactly what at least GHC's Integer does.  

indeed: (Using GHC "unboxed types" with -fglasgow-exts)

data Integer = S# Int# | J# Int# ByteArray#

Prelude GHC.Exts> case 2^20::Integer of S# i -> S# i
Prelude GHC.Exts> case 2^200::Integer of S# i -> S# i
*** Exception: <interactive>:1: Non-exhaustive patterns in case

Have a nice day,

Nobody can be exactly like me. Even I have trouble doing it.

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