Basic type refinement

[josefs]

Basic type refinement

[zuiderkwast]

The title could be "Basic type refinement" or something similar. That means, excluding an atom in the union type if it matches the pattern in a previous case/function/catch/receive clause. Only when there are no guards as a first step.

Actually, I plan to work on this on Wednesday. We have "Hackathon" at work, which means Gradualizer hacking to me. :-)

[erszcz]

I'm changing the title accordingly.

[gomoripeti]

also related to #25

your last example is puzzling. The return type of case should be the union of the type of the clauses which should still be binary | ( string() | false ). weird and good finding.

[josefs]

@erszcz, you're right that this problem is related to type refinement. Unfortunately, it might take some time before we get to implement this.

That last example is weird. Feel free to add it to test/known_problems/should_fail/ so we can keep better track of it.

[erszcz]

That last example is weird.

The mystery is solved. I have been tricked by Vim hiding the error indicator, but it did so, cause it couldn't parse a crash report. The problem is gone with 5e1c425 and both examples now behave the same.

The title issue, though, remains valid, but as far as I understand it's going to take a while before it gets solved.