ghc/haskell tool registry (was: GHC 6.8.1 on Mac OS X 10.5 (Leopard))

[Claus Reinke]

may i suggest a different approach? most shells have commands 
to list programs in PATH beyond the first match, such as 
'whereis ssh', 'which -a ssh', or 'type -a ssh'. now, this won't
help directly because the ghc tool in question might not be on
the PATH.

but as this issue is so widespread, one could extend one of the
existing haskell package registries (ghc-pkg, cabal) to cover
haskell tools as well. every haskell tool would know how to
register itself with its current location, and how to query the 
haskell tool registry for the location of other tools (preferably 
from the same build/version). since we're on the ghc list:

    ghc-tools (un-)register <path>/ghc<version>
    ghc-tools list ghc<version>
    ghc-tools describe runhaskell
    ghc-tools field location ghc-6.9
    ghc-tools field user_guide ghc-6.9
    ..

pros:

    - knowing your version would be sufficient to find
        all the tools from your bundle
    - finding all available haskell tools would be easy

downsides: 

    - tools would have to register themselves after
        installation/relocation, and unregister during 
        uninstall
    - there is no single ghc-pkg/cabal instance to choose,
        but multiple versions..

the former is no worse than for packages, the latter
is a runhaskell-style issue: we want a single ghc-tools
in the path, but we don't care who provides it.

claus

----- Original Message ----- 
From: "Simon Marlow" <simonmarhaskell at gmail.com>
To: "Christian Maeder" <Christian.Maeder at dfki.de>
Cc: "Manuel M T Chakravarty" <chak at cse.unsw.edu.au>; "GHC List" <glasgow-haskell-users at haskell.org>
Sent: Monday, November 19, 2007 9:35 AM
Subject: Re: GHC 6.8.1 on Mac OS X 10.5 (Leopard)


> Christian Maeder wrote:
>> Ian Lynagh wrote:
>>> On Sat, Nov 17, 2007 at 03:02:55PM +0000, C.M.Brown wrote:
>>>>> Is there a way for GHC on OS X to find where it was run from, so that it
>>>>> can find package.conf?
>>>> The command:
>>>>
>>>> ghc --print-libdir
>>>>
>>>> should do it.
>>> But the way that knows what to print on unix machines is that ghc is a
>>> shell script wrapper which passes -B<libdir> to the real GHC binary. If
>>> you want to be able to move GHC around then the wrapper can't have the
>>> path hardcoded.
>> 
>> The wrapper could call `pwd` to find out the current path.
> 
> pwd gives you the directory that the script was invoked *from*, not the 
> directory in which the script resides.  This is a common problem on Unix: 
> there's no general way to find out the location of a binary.
> 
> Well that's not entirely true.  On Linux you have /proc/<pid>/exe, and on 
> Solaris you have getexecname().  Does MacOS X have anything?
> 
> Cheers,
> Simon
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