Re: `map-derivation' is too slow for meaningful usage

[Ludovic Courtès]

Hi Sergio,

Sergio Pastor Pérez <sergio.pastorperez@outlook.es> skribis:

> Today I've spent some time understanding the issue with the
> `map-derivation` procedure[1]. I've submitted a fix to the issue I
> previously opened.
>
> As I describe in the answer, the procedure seems too slow for any
> meaningful usage; specially what I was describing in this thread[2].
>
> What do you think?

I haven’t taken the time to read that earlier thread and the patch you
submitted yet, sorry.

‘map-derivation’ as you noticed is not used anywhere so far and remains
kind of an experiment.  It predates package rewriting and package
transformations.  The idea was to test the feasibility of a sledgehammer
approach to dependency rewriting; from what you write, I gather there’s
room for improvement.

I prefer package transformations because they work at a higher level,
which make them easier to use.

But I’m also well aware that there are circumstances where they’re not
really applicable, such as when trying to build a variant of an entire
operating system.  I’m not sure whether operating at the derivation
level is the right approach, so your tests here are much welcome.

Perhaps we could try and address those performance issues, and then see
if we could come up maybe with a “derivation transformation” framework
to make it more approachable?

Thanks,
Ludo’.