[jhc] Compiling DrIFT with GHC >= 7.2 (was Re: [bug][jhc 7.7] about newIOArray: variable undeclared in the generated C source)

[John Meacham]

Cool. yeah, the extra Show instance will be backwards and forwards compatible.

Yeah, I am not surprised uhc didn't work due to the flags being
different, but it shouldn't be difficult. I don't have uhc set up, but
if you figure out the proper command line and add it to the
configure.in then that would be cool.

    John

On Tue, Jan 17, 2012 at 4:34 PM, Dirk Ullrich
<dirk.ullrich at googlemail.com> wrote:
> Hi John
>
> 2012/1/18 John Meacham <john at repetae.net>:
>> Hi, I'd rather have DrIFT depend only on haskell98, that will give it
>> the widest range of compilers it will work on.
> To only depend on Haskell 98 if possible to be portable is a good idea imho.
>> as far as i know, it is
>> already pure haskell 98 so it should just need the right compile flag
>> on new versions of ghc.
> You are right: passing
> --with-hcflags='-hide-all-packages -package haskell98'
> to configure does the trick ... nearly: When using GHC 7.4 even then
> `Num' seems to be no subclass of `Show' (and `Eq') anymore. But to fix
> this one only have to change one line in `src/GenUtils.hs':
>
> diff -r cb15d1da1c66 -r 5d1dc6b5a679 src/GenUtil.hs
> --- a/src/GenUtil.hs    Tue Jan 17 21:42:44 2012 +0100
> +++ b/src/GenUtil.hs    Wed Jan 18 01:04:16 2012 +0100
> @@ -482,7 +482,7 @@
>  _ `overlaps` _ = True
>
>  -- | translate a number of seconds to a string representing the
> duration expressed.
> -showDuration :: Integral a => a -> String
> +showDuration :: (Integral a, Show a) => a -> String
>  showDuration x = st "d" dayI ++ st "h" hourI ++ st "m" minI ++ show
> secI ++ "s" where
>         (dayI, hourI) = divMod hourI' 24
>         (hourI', minI) = divMod minI' 60
>
> and this adding of the `Show a' constraint to the definition of
> `showDuration' is backward compatible, isn't it?
>>
>> I tend to mainly keep jhc compatible with what is in ubuntus stable
>> release, which is ghc 7.0.2 at the moment. though patches for newer
>> versions would be appreciated of course.
> Other than DrIFT jhc does use a few of GHC's Haskell extensions (at
> least at the moment). So I guess that for jhc one have to remove the
> usage of `haskell98' package in favor of `base'.
>
> By the way: A first try to compile DrIFT with UHC
> (http://www.cs.uu.nl/wiki/UHC) fails: UHC does not understand (at
> least) the options `--make', `-hidir' or `-odir' (but `--odir').
>
> Dirk