Pack_install downgrade?

Is there a way to downgrade to an older version of a pack, or of installing a particular release version? (I couldn’t see any options for this, but I’m very good at missing things in the documentation.)

I tried specifying a URL for version 0.0.2 of rdet, and it seemed to ignore the URL and instead fetched the latest version:

1 ?- pack_install(rdet, [url('')]). % 
pack_install(rdet, [url('')]).
% Cloning into '/home/peter/.local/share/swi-prolog/pack/rdet'...
Verify package status (anonymously)
	at "" Y/n? y
% Contacting server at ... ok
% "rdet.git" was downloaded 1 times
Package:                rdet
Title:                  Runtime determinacy checker
Installed version:      1.0.0
Author:                 Raivo Laanemets <>
Home page:    
Run post installation scripts for pack "rdet" Y/n? n

2 ?- pack_install(rdet, [url(''), git(true)]).
pack_install(rdet, [url(''), git(true)]).

After some fiddling around, I figured out this work-around, but surely there’s an easier way:

  • git clone
  • git checkout -b v0.0.2 3f3a15b6cbdb1e0064e2002f07dbfe5979eb6f74
  • make package
  • pack_install(rdet, [url('file:///path/to/src/rdet-0.0.2.tgz')]).

BTW, sometimes when pack_install fails, it still ends up installing something. So, it seems safest to always do a pack_remove whenever there’s a problem.

I think it should be enough to remove the pack and do pack_install(Source), where Source is either the downloaded tar/zip file or a url to it.

That’s essentially what I ended up doing. But it seems that some of the options to pack_install ought to do that but don’t (e.g., specifying the URL in the pack_install command). Are these known problems? There’s a hint that they are known, e.g., this item in the documentation: " GIT URL (not well supported yet)"