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

John Meacham john at repetae.net
Mon Jan 23 23:28:51 CET 2012

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.


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

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