harvardpl/abcdatalog

Datalog that's as easy as ABC.

abcdatalog's Issues

Run tests in CI

We should add a GitHub Action that packages the project and runs tests when PRs are made.

UI/UX Improvement

First, thank you to the authors for this wonderful tool.

I think there are a lot of improvements that can be made in terms of the interface and user experience. Some little additions can bring this program a long way and make it much more convenient for students to use.

Some suggestions

• Changing the Look and Feel to FlatLaF. This would bring about the most difference with about 4 lines of code given the dependencies are met upon compilation. In short, this is the look and feel of JetBrains IDEs.
• Changing the font to something more readable like JetBrains Mono
• Adding an edit menu with standard editing controls (Undo, Redo, Cut, Copy, Paste, Select All, Clear All, etc.). Some of these could be implemented cleanly by extending JTextArea.
• Adding a view menu with at least the following (Zoom in, Zoom out, Restore default zoom). In addition, having the option to switch to a vertical view (editors are side by side rather than on top of each other)
• Parentheses completion
• Adding accelerators and mnemonics to the menus and menu items

Beyond these additions, there are a couple of line operations that could be very convenient (ones that I wish I had when completing assignments with the tool)

• Delete current line
• Duplicate current line
• Move lines up/down

I have experience with Swing and desktop development, and I am more than willing to spearhead these changes. No changes are needed to anything but the gui directory.

Add tests for Datalog executors

We should add a couple basic tests for the DatalogParallelExecutor class (to avoid issues like #11).

Maven does not run JUnit tests

Currently, tests are not run when the project is packaged because Maven does not know where to find them. The project should be restructured so that tests are in the src/test/java directory (following Maven conventions).

Bug with extensible predicates and parallel executor

I tried running the "ExecutorExample" program and encountered this exception:

Exception in thread "main" java.lang.IllegalArgumentException: Predicate true is not marked as extensible.
	at edu.harvard.seas.pl.abcdatalog.engine.bottomup.concurrent.ExtensibleBottomUpEvalManager.addFact(ExtensibleBottomUpEvalManager.java:182)
	at edu.harvard.seas.pl.abcdatalog.engine.bottomup.concurrent.ExtensibleBottomUpEvalManager.eval(ExtensibleBottomUpEvalManager.java:123)
	at edu.harvard.seas.pl.abcdatalog.executor.DatalogParallelExecutor.start(DatalogParallelExecutor.java:90)
	at edu.harvard.seas.pl.abcdatalog.executor.ExecutorExample.main(ExecutorExample.java:122)

After some poking around I found there is a fact "true" that always gets added to the list of initial facts:

AbcDatalog/src/main/java/edu/harvard/seas/pl/abcdatalog/ast/validation/DatalogValidator.java

Line 101 in 493d24a

rewrittenClauses.add(new ValidClause(True.getTrueAtom(), Collections.emptyList()));

The example uses the DatalogParallelExecutor, which uses the ExtensibleBottomUpEvalManager.
The exception is thrown here when trying to add the "true" fact:

AbcDatalog/src/main/java/edu/harvard/seas/pl/abcdatalog/engine/bottomup/concurrent/ExtensibleBottomUpEvalManager.java

Lines 179 to 183 in 493d24a

	public void addFact(PositiveAtom fact) {
	if (!this.extensiblePreds.contains(fact.getPred())) {
	throw new IllegalArgumentException(
	"Predicate " + fact.getPred().getSym() + " is not marked as extensible.");
	}

In the example file, the executor is initialized here:

AbcDatalog/src/main/java/edu/harvard/seas/pl/abcdatalog/executor/ExecutorExample.java

Lines 94 to 95 in 493d24a

	DatalogParallelExecutor ex = new DatalogParallelExecutor();
	ex.initialize(ast, Collections.singleton(edge));

However, there doesn't seem to be a way to add the "true" predicate here as it is private.
Thus, it seems this exception will occur whenever the DatalogParallelExecutor is used.

UI suggestion: overtype closing parenthesis

I have a small UI suggestion that should complement the autocompleting parentheses feature: "overtyping" closing brackets. This would allow users to type over an existing closing bracket without adding an extra bracket.
For example, when typing edge(a, b)., one first types edge(, which automatically creates the closing bracket, resulting in the text edge(). Without this feature, users would have to manually move their cursor around the existing closing bracket.

This is the standard behavior in text editors such as VSCode and Sublime Text (https://stackoverflow.com/questions/75002527/how-editor-autoclosingovertype-works-in-vscode-settings).

I have a patch to implement this, and I'm happy to submit a PR. I just wanted to check whether you would welcome this change to the UI.