cabal setup scripts (was: Re: building haddock?)

Frederik Eaton frederik at
Tue Feb 7 22:34:44 EST 2006

I haven't been following this closely, but I think I have to agree
with Isaac on this point. To me it seems that the .cabal language is
already Turing complete in the sense that one can get it do anything
by writing to the Haskell mailing lists. That's neither efficient for
the users, nor for Isaac.

(However, I do think it would be much nicer if one could use say
"cabal-setup" or just "cabal" instead of "runhaskell Setup.hs"...)

> While we're talking philosophy maybe I can let you in on the
> philosophy behind the Setup script.  One problem with domain-specific
> declarative languages like the .cabal file is that they grow into
> (ugly) turing complete programming languages.  I would prefer to keep
> cabal rather simple (it's already almost too complex, IMO) and yes,
> push the complexity into the setup script.  You may see it as passing
> the buck, I see it as allowing the end user to program in a beautiful
> language for those inevitable turing-tasks.
> Cabal can and should leverage abstraction where it appears, such as
> preprocessors and Programs (which it can detect and add nice flags
> like --with-foo-path= and --with-foo-args=).
> You did seem to recognize the necessity for escaping to a
> turing-complete language in your build-style: custom proposal.
> Indeed, your proposal requires us to bail out to a turing complete
> language in exactly the same circumstances as the current situation.
> peace,
>   isaac
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