Build system idea

[Duncan Coutts]

On Thu, 2008-08-28 at 15:02 +0100, Simon Peyton-Jones wrote:
> | Yes this means that Cabal is less general than autoconf.  It was quite a
> | revelation when we discovered this during the design of Cabal - originally
> | we were going to have everything done programmatically in the Setup.hs
> | file, but then we realised that having the package configuration available
> | *as data* gave us a lot more scope for automation, albeit at the expense of
> | some generality.
> 
> Now there's a useful insight for the paper I hope Duncan (or someone) is going to write
> 
>         configuration as code [autoconf]
> vs
>         configuration as data [cabal]

and there are more fine distinctions even than that. Each change in the
power of the language used for configuration changes the range of things
that the developer and packager/user can do, and in opposite directions.
It's fairly similar to the tradeoffs between deep and shalow embeddings,
but I think we more intermediate points. The challenge is in
characterising the relationship between the language and the things the
developer and packager can do so that we can pick a useful point (or
points) in that tradeoff.

Before anyone thinks about writing a paper on this topic, I recommend
you read all of Eelco's papers[1] first just to make sure he's not
already done it! :-) Which is another point that there's lots that Cabal
(and ghc) can learn from Nix and related stuff.

Duncan

[1] http://nixos.org/docs/papers.html