[Haskell-cafe] fyi GHC 7.2.1 release on the benchmarks game

[austin seipp]

Hello Isaac,

On Fri, Aug 12, 2011 at 10:18 AM, Isaac Gouy <igouy2 at yahoo.com> wrote:
> 1) Some of the GHC programs contributed to the benchmarks game have problems with recent GHC releases
>
> - meteor-contest #5 - Ambiguous occurrence `permutations'
>
> http://shootout.alioth.debian.org/u64q/program.php?test=meteor&lang=ghc&id=5#log

This can be fixed by changing the line:

import Data.List

to:

import Data.List hiding (permutations)

Also, the program needs to be compiled with -XBangPatterns

> - regex-dna #2 - Precedence parsing error
>
> http://shootout.alioth.debian.org/u64q/program.php?test=regexdna&lang=ghc&id=2#log

This can be fixed by changing this line (line 74):

mapM_ putStrLn $ results `using` parList rdeepseq

to:

mapM_ putStrLn (results `using` parList rdeepseq)

There are also some deprecation warnings related to `rwhnf` among
others being renamed, but those are harmless (may want to fix them
anyway though.)

> - reverse-complement #2 - parse error on input `->'
>
> http://shootout.alioth.debian.org/u64q/program.php?test=revcomp&lang=ghc&id=2#log
>

You can fix this by adding this pragma:

{-# LANGUAGE MagicHash, UnboxedTuples #-}

or compiling with -XMagicHash and -XUnboxedTuples

Also, this program imports 'GHC.IOBase' which is a warning, that
import should be changed to 'GHC.IO' instead.

> - reverse-complement #3 - Could not find module `Monad'
>
> http://shootout.alioth.debian.org/u64q/program.php?test=revcomp&lang=ghc&id=3#log

You can fix this one by adding this pragma to the top of revcomp.hs

{-# LANGUAGE BangPatterns #-}

Alternatively you can compile with -XBangPatterns. Also, change the line

import Monad

to:

import Control.Monad

> 2) I noticed `-fvia-C` has now gone away and there were half-a-dozen programs that had been written to use `-fvia-C` so how might that effect performance of those programs?

I can't forsee the potential performance ramifications, but frankly
-fvia-C has been deprecated/not-advised-for-use for quite a while now,
and I wonder how many of these programs just have not been
updated/tested with the native code generator since they were written.

In any case it's not an option anymore, so your only choice is to nuke
it from orbit (orbit being the Makefiles.)

-- 
Regards,
Austin