Re: Parameterized packages

["Ludovic Courtès" <ludo@gnu.org>]

Hi,

zimoun <zimon.toutoune@gmail.com> skribis:

> To be clear, the seed (bootstrap) fixes how the compilers OCaml@4.01,
> OCaml@4.07, OCaml@4.09, CPython@2.7, CPython@3.5, CPython@3.6, PyPy
> (not yet in Guix), GCC@8, GCC@9, Clang@8, Clang@9, etc are compiled.
> Then, it is difficult to use them to compile a package with one of
> them.
>
> Do we end with 'package-with-ocaml4.01', 'package-with-ocaml4.07',
> 'package-with-ocaml4.09', 'package-with-python2',
> 'package-with-python3.5', 'package-with-python3.6',
> 'package-with-pypy', 'package-with-gcc8', 'package-with-gcc9', etc.?
>
> Do the users have to write all these 'package-with-<version>'?
> And if one wants to use CPython@3.5 and GCC@8, does they need to
> define the package using:
>
> (define-public my-foo
>   (package-with-python3.5
>        (package-with-gcc8 foo)))
>
> ?
>
> I feel something is lacking.

I agree.  ‘package-input-rewriting’ gives us almost what you want, with
the limitation that implicit inputs are ignored (which is a good thing
sometimes, and a problem in cases where you want to experiment with
toolchains, as you write).

What we’d need is a variant of ‘package-input-rewriting’ that somehow
walks through implicit dependencies.  It could do that by changing the
build system, I guess.

Thanks,
Ludo’.