Added watch.sh

[johannesloetzsch]

Use inotifywait (from inotify-tools) to rebuild everytime the SOURCE changed

[johannesloetzsch]

Till now, there is one minor issue:
In case of syntax errors, doclog.sh keeps running, prompting the user in a prolog repl.
When using watch.sh this is not intended. It would be nice to exit doclog after errors instead.

I could work around this in watch.sh but I would prefer, to have this as default behavior of doclog.sh. What do you think @aarroyoc ?

[aarroyoc]

It should be possible to add a catch/3 that prevents going back to the REPL. Give me a few days

[johannesloetzsch]

It should be possible to add a catch/3 that prevents going back to the REPL. Give me a few days

Thank you :)

Even without I used DocLog with watch.sh quite extensively and successful :)
Till now when errors occur. Ctrl+d closes the repl and continues the watch loop.

I wrote a little tutorial about how to use prolog + scryer + playground. I assume I will push it soon and will let you know than…

Are you interested in a listing of issues, workarounds and error messages I experienced, while working with DocLog?

[triska]

It should be possible to add a catch/3 that prevents going back to the REPL.

One elegant and also more generally useful way to solve this would be to add a -t Goal command line option to Scryer Prolog itself, which would specify the Goal to use as the toplevel.

For instance, by specifying -t halt, we would invoke Scryer Prolog in such a way that any goals are run, and then the process halts, no matter in which way the "toplevel" was reached, i.e., whether the initialization and any given goals succeeded, failed or resulted in an exception.

[triska]

Previous related discussion: mthom/scryer-prolog#187 (comment)

[aarroyoc]

While we implement that on Scryer, I pushed a commit that wraps everything in a catch/3. Let me know if it works for you

@triska maybe that flag deserves its own issue as the original one was closed

[johannesloetzsch]

@triska Thanks for your support :) -t halt sounds like a good improvement in the future

@aarroyoc Thank you for the catch wrap :) I tested it and it works for many cases.
I added a little change to print the error message before halting.

There are some cases when the catch is not enough. Here an example in case you would like to reproduce:

• edit doclog.config.pl and add a bug like trying to use page/4 instead of page/3:

page("Test page", "First steps", "test-page.dj", "this causes an error")

When starting DocLog, I get:

% Warning: initialization failed for: run("~/src/prolog/scryer-prolog","~/src/prolog/scryer-prolog/target")
?- 

Obviously parsing the config was not catched.

In practice there is one case I had several times, when I produced syntax-errors in the config:
For adding new pages, I copied the entry of the last page and adopted it, but forget to add a comma to the now second last entry.

If you have a simple fix for catching syntax-errors during initialization (e.g. by consulting the config from main inside the catch) I appreciate it. If not, it should be fine too.

From my perspective the feature works well enough to be merged.

[triska]

Not yet having a -t switch, an appropriate construct could be call_cleanup/2 from library(iso_ext): It reliably performs the cleanup, which in this case would be halt.

[triska]

maybe that flag deserves its own issue as the original one was closed

Yes thank you, good point, I have filed mthom/scryer-prolog#2651 for it!

[triska]

As mentioned by @hurufu in mthom/scryer-prolog#2651 (comment), multiple -g switches can be used, so adding -g halt to the invocation may suffice to solve this more elegantly!

[aarroyoc]

Does the proposed solution by @triska work for you?

[johannesloetzsch]

Does the proposed solution by @triska work for you?

Yes, seems to work well :)

From my side, this PR is ready to be merged

[triska]

-g halt should work.

[triska]

As mentioned, I think -g halt would work.