Hello,

> We could use a thunk field to write something like:
>
> --8<---------------cut here---------------start------------->8---
> (define (default-locale-libcs ...)
>   (if target glibc (canonical-package glibc))
> --8<---------------cut here---------------end--------------->8---
>
> But I'd like to avoid that. I'll see if I can figure out something
> better after a good night.

Couldn't find much better, here's a patch, tell my what you think!

Thanks,

Mathieu