I’m using: SWI-Prolog version ??? (threaded, 64 bits, version 8.0.3) on Ubuntu 18.10, today I typed help(open) and I saw the output in the console! Then I tried opening the Prolog Help from the PceEmacs window and again the output came out in the console?!?!?!
I was expecting the nice X11 window with the tree on the left and content on the right. Has that been removed, have I not configed something? As much as I live in the command line, I find it hard to be paging up and down in the terminal.
Nothing. The local online help just dumps to the console, if possible piping through less. The old X11 version has been deleted some versions back. I think most people use the online manual at swi-prolog.org. The local one has of the advantage that it really matches the installed system, whereas the online manual always reflects the last development release.
You can also start swipl --pldoc which opens your browser on the documentation system, providing docs for your application as well as the local manual. The only downside is that there is no autocompletion on search.
The HTML docs are in doc/Manual in the installation directory.
I’m glad that the old X11 version has been deleted … sometimes I use swipl with only a terminal window and it was annoying that help/1 would try (and fail) to pop up an X11 window (there doesn’t seem to be an option for turning off X11 (like emacs -nw), despite there being two Linux packages: swi-prolog-x and swi-prolog-nox).
swi-prolog-nox definitely doesn’t open X11 windows as it has no way to do so. Turning X11 access off while it is installed is done by ensuring DISPLAY is not set or using swipl --no-pce.
What was the last version that included the X11 help window? I miss it badly. I am willing to go back to an earlier version just to have that X11 help window.
It is not very likely to happen as it requires quite a bit of work. The old stuff was removed because the underlying software was old and unmaintained. Building the docs was a nightmare so bad that the docs were distributed separately from the sources There are several alternatives though:
If you load PlDoc, you can use your browser to browse the the systems docs as well as the code you documented yourself.
help/1 and apropos/1 that dumps the docs on the terminal.
The last three options provide you with a local version that reflects your installed version. I guess the terminal version would need some way to do interactive jumping to linked pages.
There are several alternatives though: