moving from ghc-6.2 to 6.4

[Simon Marlow]

On 29 March 2005 08:59, Johannes Waldmann wrote:

> I am trying to bring a larger heap of code
> (http://141.57.11.163/auto/ ) into 6.4 land (because of wonder
> stories about faster compilation, faster execution, Data.Map, and so
> on ...) 
> Here are a few observations and questions
> that may be useful to others as well.
> 
> * what is the situation with ghc-6.4 for sparc/solaris?
>    I don't see a binary package in the download area.
>    I started to build from source - can this be successful?
> 
>    (The rest of this report refers to i386/linux)

There are some outstanding issues on Sparc/Solaris that I didn't get
around to investigating before the release.  One of them is a random
crash, so you should probably consider 6.4 to be broken on Sparc/Solaris
for the time being (it might be related to gcc version though: 6.2.x
might be just as broken with recent gcc versions).  I'm keen to get more
data points, if you have the time & inclination to test it.

We could really do with a Sparc/GHC guru to take up the mantle of
maintaining the Sparc port - it's kind of hard for us to do it without
the hardware locally, and I'm no Sparc expert.

> * Cabal is very nice! - The only thing that was confusing me
>    is that I have to list all modules in the *.cabal file:
>    if I don't, it still happily builds and installs the package
>    but it cannot be used, giving linker errors. Couldn't this be
>    checked earlier? Or better, couldn't it infer the needed
>    hidden modules? Anyway I can generate the module list by a shell
>    script but that does not feel right. - How do I build and install
>    a profiling version of a package, how does Cabal support this?

The module list: yes, I think this is something the Cabal team would
like to automate in the future.  There's no way to build profiled
packages at the moment, as far as I'm aware.  I agree it's an important
feature, though.
 
> * I don't see "dramatic" improvements in execution times -
>    are there some magic ghc options I missed? I used -O -fvia-C.
>    Still, executables are maybe 2 .. 5 % smaller and faster than they
>    were with 6.2 - and compilation without -O is really fast.

I don't know where this rumour of dramatic improvements in execution
time comes from :-)  Our testing shows modest improvements in most
programs, with some programs going slower.  The focus of 6.4 wasn't
really on performance, but we hope to merge performance improvements
back into future 6.4 releases.

Cheers,
	Simon