[Haskell-cafe] OSX i386/x86 and x86_64 - time to switch supported platforms?

[Edward Amsden]

Steve Severance <steve at medwizard.net> wrote:
> Moving from x86 to x64 has advantages and disadvantages from my POV.
> Advantages:
>  * Able to address more memory
>  * More registers for code generation
>  * Haskell dependencies wouldn't need to be built for x86 on Snow
>    Leopard (though if we swapped to x64 on Leopard as well, the Leopard
>    users would start having to build 64-bit libraries specially)

If we keep the capability to build both, and come up with a good way
to use the platform default, this would be the biggest advantage for
OS X users. (Full disclosure: speaking as a Snow Leopard user). Also,
as time goes on, we will be seeing more, not less, 64-bit OS X users
and releases.

> Disadvantages:
>  * Pointers become wider, and Haskell data structures mostly consist
> of pointers. This will bloat memory use of Haskell programs.

I'd be interested to see how much this happens in practice, but it
does seem to be a big concern.

>  * Generated binaries won't work on older Macs that don't have a
> 64-bit OS/CPU. This is important if you are distributing compiled
> Haskell binaries, which is not something I personally do but which is
> probably important to support

The compilers/linkers for most languages supported on OS X support
generating "universal" binaries with both 32- and 64- bit code. I
wonder if this is something GHC could support?