Solve the halting problem

[Rich-Harris]

it's really annoying when you're in the middle of typing a for loop...

for (let i = 0; i < things.length; <cursor>)

...and the code starts running before you have a chance to write i += 1. Similarly if you're trying to write this...

while (true) {
  // some code...
  if (someConditionIsMet()) break;
}

...you will get as far as while (true) {, it will add the closing }, and you're screwed.

Maybe not the easiest thing to fix, and certainly not in a general way, but I wonder if there's something that can be done to handle common cases. Like, idk, not running the code if the cursor is currently inside a loop?

[ghost]

Maybe a mode (like JSFiddle) where it doesn't re-parse / execute until you tell it to?

[mallsoft]

Maybe a floating button inline that lets you "merge" the last written code so it doesn't evaluate anything before you are done typing things?
This could be expanded upon to mean all code and not just loops.
If it's really that important to get that super instant feedback, could a shortcut for the "merging" functionality suffice?

[Rich-Harris]

I think a 'run when i say' mode would be a good addition, yeah. I still kinda like defaulting to instant feedback, I find I work much quicker that way. Maybe the best UX is somewhere in between the two extremes

[pngwn]

If we decide to disable running when the cursor is inside the loop what if you make a genuine mistake but don't move your cursor? Then you have no feedback at all and you might not know what you've done wrong immediately. Maybe we can provide a REPL specific error to provide the required feedback.

[ghost]

We could also expose the currently hard-coded CodeMirror options for auto brackets and such, but won't help in the case of the for loop example. I know I'd like to have tab sizes a wee bit bigger than 2 spaces personally and auto-quoting drives me nuts :)

[dhonx]

@Rich-Harris , Maybe this could solve ? See 👉 JSBin/loop-protect

[Conduitry]

That library is implemented as a Babel transform, so we wouldn't want to use it as is. But it might be an interesting idea to steal and implement as a preprocessor that walks the AST and looks for these loops.

[dhonx]

Ya... exactly...

that is what i mean... i read the source code.. its too complex for me,, maybe we can simplify that... are you working on it now @Conduitry ??

[weepy]

Could you just prevent instant reload if the cursor is within a loop parentheses?

[mustafa0x]

#55 (handle_change should be debounced) could help with this — you would just have to keep typing within the debounce timeout (200ms probably makes sense).