Too much output when using quad ⎕

[rikedyp]

To Reproduce
Steps to reproduce the behavior:

1. Go to https://problems.tryapl.org/
2. Scroll down to sample problem input
3. Try {⎕←'ok'}¨

We should probably suppress ⎕ and ⍞ output if possible, but it's low priority (anyone who knows what ⎕ and ⍞ do should be able to figure out what's going on)

[abrudz]

Will go away when we switch to TryAPL-based execution

[ghost]

With ATO-based execution and the "user feedback" improvement this case will output nothing. rx.exec(...) returns null for ⎕←, ⎕off, etc.

[abrudz]

Since we've switched to ATO backend, the issue is now (ironically) too little output.

[ghost]

Does '...should have returned 3 with ('COOLAPL') as right argument.' sound appropriate for early halting expressions? (To clarify these expressions return un-expected output, or often errors - which we ignore. I think it's ok, though naive, to simply detect the null and ignore the details)

[abrudz]

Yes, I think so. Though technically {⎕←'huh' ⋄ +/⍵∊'AEIOU'} should/could(?) pass…

[ghost]

That's a good point, handling that would require changes to the framework, or possibly subsequent requests for round-tripping purposes.