Issue with pack_install not accepting GitHub URLs

Hey everyone,

I’ve been encountering an unexpected issue with pack_install in SWI-Prolog version 9.2.0. It seems that it mysteriously stopped accepting GitHub URLs, causing errors during installation. I’m attempting to install Prolog packs directly from GitHub using pack_install. Here’s an example of the URL I’m trying to install:


I’m using: SWI-Prolog version 9.2.0

I want the code to: Install packages from GitHub using pack_install.

But what I’m getting is: Type errors indicating that text was expected but version([0,1,4]) were found.

My code looks like this:

?- pack_install('').
ERROR: Type error: `text' expected, found `version([0,1,4])' (a compound)

It seems like pack_install is not interpreting the version numbers correctly when provided with GitHub URLs.

Has anyone else experienced this issue or knows of a workaround? Any help would be greatly appreciated!


This bug is already fixed in the git version. The work-around is to use either

?- pack_install(date_time, [url('')]).

Or, more easily

?- pack_install(date_time).

Nor, yet more easily

swipl pack install date_time

If you want a specific version

swipl pack install --version =0.1.4 date_time

Thank you so much, Jan! I’ll proceed with the work-around. Your timely response is greatly appreciated!

I’d like to learn more about these features. However, I couldn’t locate them on the SWI-Prolog -- Command line options page. Could you please direct me to where I can find information on them?"

See SWI-Prolog -- SWI-Prolog app scripts

Jan, your support truly exemplifies world-class service. Thank you!