[Nix-dev] Re: May I remove the old python code?

[Ludovic Courtès]

Hello,

"Andres Loeh" <andres.loeh at googlemail.com>
writes:

> One other issue, I think, might not apply to an interpreted language
> like python, but
> it does apply to libs for compiled languages like Haskell that tend to
> be binary-incompatible
> between any two versions. If there actually is a build process
> involved, you have to select
> the compiler for which you want to build the library. If multiple
> versions of a compiler are
> around, and you still want to install via nix-env, you have to
> multiply all libraries for all
> compiler versions. A wrapper approach, on the other hand, makes this very easy.

What does "multiply all libraries for all compiler versions" mean?  In
practice it boils down to applying a function to different compiler
versions.

Think of kernel-dependent packages: we have `kernelPackagesFor', which
takes a Linux kernel and returns a set of kernel-dependent packages, and
then`configuration.nix' can specify a `kernelPackages' function.  The
same approach could be used for Haskell or any other language.  The
build farm admins can then choose to build whichever `kernelPackages'
(or `ghcPackages', etc.) are important to them.

Thanks,
Ludo'.