On Fri, Nov 10 2017, Chris Marusich wrote:
> Anecdotally, I swear I've seen guix build some things from source even
> when I did not specify --fallback.  Has anybody else seen that occur?

Yeah, I've definitely seen that. My assumption was that this is what's
meant to happen when substitutes aren't available. So if I write a
custom package and install it (with "guix package -f") it will build it
locally, even without --fallback.

I assume that --fallback builds the package if the substitute exists,
but fails to download for some reason (network error, etc.).

Carlo