I started (and stalled, though not permanently I hope) on a similar idea, to offer as part of the library infrastructure. Mine was somewhat more complex, maybe too much so, dealing with a combination of static and dynamic information, and also hoping to circumvent or minimize the CPP problem. Copies of the initial code and test module are at: http://www.ninebynine.org/Software/HaskellUtils/LibraryInfrastructure/Distri... http://www.ninebynine.org/Software/HaskellUtils/LibraryInfrastructure/Distri... #g -- At 10:59 07/04/04 +0100, Simon Peyton-Jones wrote:

Library folk

Below is a suggestion from George that initially appears to be about Template Haskell: access to the GHC version identity. But of course it's not strictly a TH thing: we could simply provide a module

module GHC.Version where ghcVersion :: Int

and then you could import that module anywhere, including in your TH program:

import GHC.Version $( if ghcVersion > ... then ... )

And indeed such a thing might be more generally useful, across all Haskell implementations not just GHC. Perhaps it should be

module System.Compiler where compilerName :: String releaseDate :: CalendarTime -- or (Day,Month,Year)? version :: (Int,Int) patchLevel :: Int

So then a program could ask whether it was being run by Hugs or GHC or whatever.

Questions:

* Would this be a good thing to agree across compilers?

* What should the interface be? I gave one possibility above; George gives another.

* I imagine this'd be useful for the library infrastructure project, somehow.

Would anyone like to run with this to get an interface agreed? From the GHC end we'd be happy to implement any agreed interface.

Simon

-----Original Message----- From: George Russell [mailto:ger@informatik.uni-bremen.de] Sent: 07 April 2004 10:46 To: Simon Peyton-Jones Subject: Re: mkName and qualified names

George Russell wrote:

...

incidentally you asked for priorities. Mine are (still)

Oh, and another one, (3) access to the current GHC version. For example

data GhcVersion

instance Read GhcVersion instance Ord GhcVersion

thisVersion :: GhcVersion

then you can do $( if thisVersion >= read "6.4.1" then [dd| -- use whizzo new features ... |] else [dd| -- sigh. painful workaround for Luddites ... |] )

This isn't nearly as important to me as the other two suggestions I made, however I presume it would be easier to implement.

best wishes and thanks,

George _______________________________________________ Libraries mailing list Libraries@haskell.org http://www.haskell.org/mailman/listinfo/libraries

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