Lars-Dominik Braun <l...@leibniz-psychology.org> writes:
> this issue is similar to https://issues.guix.gnu.org/41702, but I’m not sure > it’s exactly the same. For guix-science I’m trying to provide some packages > like python-jupyterlab, which depend on a mix of packages from guix proper and > newer versions of packages already included in guix proper. Thus I need to > rewrite inputs of the former to the latter. (Because Python only propagates > dependencies and thus collisions would occur.) > > Previously I have been doing this using package-input-rewriting, but starting > an environment containing python-jupyterlab alone took about 20s (warm caches, > all derivations in the store). Manually rewriting inputs by inheriting and > alist-delete’ing brings this down to 3s, which is pretty significant. Could you show us a concrete example? Input rewriting is recursive and will traverse the whole package graph by default, even if you *know* that, say, GCC doesn’t need to be rewritten. For the more generic “package-mapping” you can provide a “cut?” procedure to determine when to stop recursion. Perhaps this would make things faster in your case? -- Ricardo
