Progressing the SWI-Prolog environment

[stassa.p]

Uh oh, I see I posted my previous comment about history in this thread by mistake. I meant to post it in this new topic:

Command line history gone

I reported some issues I had with the new SWI version 3.33 in this thread: To be able to work as fast as before while I get used to the new Epilog console and editor, I’ve re-installed my previous Prolog version, 9.3.24, alongside the new one. After I did that, I noticed that I no longer have any command-line history in any of my Prolog projects. What I mean by that is that up-arrow doesn’t fill in any commands, and ?- !!. says there’s nothing there: 1 ?- !!. ! No such event ! No such even…

Apologies for the confusion. I guess the newer topic can be merged into this one?

@jan

I think that explains some of the situation. If the system has a commandline editor, it by default does not initialize the !! based history. That is mainly because some people do not like that ! can get ambiguous at the toplevel. You can enable !! based history using

:- set_prolog_flag(history, 50).

in your init.pl (adjust 50 to the number of commands you want to be recalled).

I added that in my init.pl file in an effort to resolve my history issues, but I still don’t get any history in the newer versions (9.3.24 and 9.3.33, which I keep referring to as 3.33- sorry).

Btw, I guess all versions pick up the same init.pl file so that could cause trouble, for instance if there’s a readline setting for one version that’s not supported by another. Is there a way to have an init.pl file specific to a version, e.g. in a folder named the same as a version? Sounds hacky though.

@jan

Next, the versions before the move the SDL used a little Win32 console I wrong ages ago in native Windows code. The new one uses the Epilog terminal emulator in xpce and then uses BSD libedit for the commandline editor. The _HiStOrY_V2_ comes from the history save/load of this commandline editor. Before that, the old console used a different format for saving the history.

Thanks, that clarifies things a bit. So the history files written by earlier versions (prior to the switch to SDL?) can’t be read, or updated by, newer versions (after the switch)?

@jan

• Remove (or empty) the dir-history directory in the config dir to get rid of the old history
• Make sure there is no setting for the readline Prolog flag in init.pl.

So that’s where the history is! The hint is in the name I guess

I can also see a dir_history.bak for backup I guess.

I had a look in my dir_history and there’s a bunch of files (40 of them) in there that hold the history for all my projects going back to 2022. They’re just plaintext files so I can see all the stored commands in my text editor. I like that! But if I remove dir-history then I lose all of them. That I don’t like!

The files in dir_history are named with hashes that I’m guessing must record the path to the directory of the Prolog session that created the history file. Is that correct?

Is there a way to re-activate those history files, and make them available to their respective SWI-Prolog sessions again in the newer SWI-Prolog versions? By “respective” I mean any SWI-Prolog session starting from the same directory as the session that originally created the history file (assuming my model about that is correct)?

I would really like to be able to hold on to my command history. I start so many different projects that it’s difficult to remember what I was doing in every one. I usually document the important queries but not always.

Clearly, I have some attachment issues.