On Thu, 2006-07-06 at 12:12 +0100, Duncan Coutts wrote:

On Thu, 2006-07-06 at 10:43 +0100, Duncan Coutts wrote:

...

Hi Cabal hackers,

For c2hs we've run into a problem. See the thread about c2hs on window over on the haskell list.

c2hs wants to install a data file (actually a .hs source file) and wants to know where it's been installed so that c2hs --copy-library can find and copy said file.

So how do we do this? At the moment c2hs's Setup.hs calls a postInst script which installs a wrapper script (much like all the little ghc wrapper scripts which specifies the path where things can be found). Of course this doesn't work on Windows.

I recall some talk about making this sort of thing easier? Where did we get with that?

Ah, I think I can answer my own question.

There is a "data-files" field one can add to the cabal file and the recent Paths_${projname}.hs thing allows us to find the data files at runtime.

So I'll go try to hack that into c2hs so it'll work on win32.

Ok, along a similar theme... We provide the Paths_${projname}.hs module, as a little extra there it provides the current version number. Perhaps we could generalise that and provide the whole cabal file (using the normal Cabal types). My motivation in this case is that c2hs currently gets more fields from the .cabal file than it conveniently provides. The c2hs Version.hs.in file: name = "C->Haskell Compiler" versnum = @C2HS_VERSION@ versnick = @C2HS_NICK@ date = @C2HS_DATE@ version = name ++ ", version " ++ versnum ++ " " ++ versnick ++ ", " ++ date copyright = "@C2HS_COPYRIGHT@" disclaimer = "This software is distributed under the \ these @@ var substitutions are done by configure, which actually gets the values of the vars by grepping c2hs.cabal ! dnl This is far from elegant, but works for extracting the plain version number C2HS_VERSION=`$GREP '^Version:' c2hs.cabal \ | $SED '-e s/Version:[[ ]]*//'` C2HS_NICK=`$GREP '^--Versnick:' c2hs.cabal \ | $SED '-e s/--Versnick:[[ ]]*//'` C2HS_DATE=`$GREP '^--Versdate:' c2hs.cabal \ | $SED '-e s/--Versdate:[[ ]]*//'` C2HS_COPYRIGHT=`$GREP '^Copyright:' c2hs.cabal \ | $SED '-e s/Copyright:[[ ]]*//'` note that this includes two pseudo fields which are kept as comments in the .cabal file: Name: c2hs Version: 0.14.6 --Versnick: "Travelling Lightly" --Versdate: "28 Apr 2006" License: GPL etc... Now we already allow extra extension fields in the .cabal files without complaining (of the form "x-foo:"). Perhaps we could include these extension fields in the cabal ADT as just a simple string key->value mapping. Or perhaps it should be [String] as the value type, parsing using the normal ',' as seperator and using "" quotes to make things single items. That way, the app could keep this kind of info in one place and extract it at runtime for things like version messages and about boxes etc. Duncan