On Wed, Jan 13, 2021 at 03:44:41PM -0500, Leo Famulari wrote:

> You might spend a loooooong time building things but it depends on the
> specific package(s).

I would argue that while using time-machine one does not expect
substitutes to be available, any way, since the old binaries are removed
by the substitute provider as the time goes by. It that’s not true, a
possibility to avoid the long build time problem, I think, is to perform
`guix time-machine --commit --channels -- build --no-substitutes` for
the offending package, only, before `environment`, the latter with the
substitutes permitted.

I will retry now my attempts to fix the r-foreign problem with
--no-substitutes added.

WŻ