Hegel: Lots of examples broken

[srg-kostyrko]

after https://github.com/JSMonk/hegel/pull/117 was merged lots of examples in docs got broken - they report errors when docs say there should be none like in

https://hegel.js.org/try#PTAEDEFcDsGMBcCWB7aoAiBTWAbAhgE55KoBQAZjAimgM6QC2AjABR4Bco0jARpgQBpQPTtwZ8CASlG9+oAN6lQoApniQCaPKADUwgNykAvqVIgIVEmgCiADwAOq2rRqlYqWvFD0GAJlAAvKCUcFagbDLi-EIiXLJSkRIKSipqGlq6Bsam5gCCBATIAO4WoTSgdo6Yzq7u0J7ejADMgeEccVGCwon80h1JAQB8oNp6PIakPqxMQr6SoOaAvBuAMjsAhJOMviwzoHMLYCvrPk3bs-NLazlg1gXIBJwAKgCe9pigAETkeDi0mO+giFoALgyAY9mIiB4ODeRUQ8AAFqB4C83u8xBJ3htmCwvj9MEJ3u9JBNzDdCvdQM9Xh8AOQ0-6A4HuMEQqEwuGI5HUtHxTE+LaEoQAFmJVwqtwpVNRNKY9IBQMQIJZSDZoFhCKRKI+6P4fOaLHeTHeBN8RMMQA

one more point about this check is that promise chaining will report an error if we make some side effects in then and does not care about the returned promise

https://hegel.js.org/try#IYZwngdgxgBAZgV2gFwJYHsIxACgJQwDeAvgFCm54B0yAFgKYQ74wC8AfEaTDAPS8wAJumzoAtvWypBk+nDj0oyEKWJ4gA

tough this is not a very good approach I would say - so not sure if something needs to be changed here

[JSMonk]

Ahh. Can you try to fix the examples? I will fix the behavior with async functions that return Promise<undefined>.

[srg-kostyrko]

I started working on examples
will add here other findings

[srg-kostyrko]

Array.push returns the new length of an array that rarely is being used but is reported as an error now

http://localhost:3000/try/#MYewdgzgLgBAJiArgIwDYFMIC4YEEBO+AhgJ4A8YiAtsuvgHwwC8MA2gLJFQAWAdAAoBJADQxOPXgFEAugG4AUPIQoMEXgAdEEbgAoALACYAlAqA

[JSMonk]

Oh, it's a problem, because everybody uses push without using his return value

[srg-kostyrko]

yeh, and the same is actually true for methods that mutate array in-place like reverse or splice - they have return value but usually used without using it

[srg-kostyrko]

other problem - Date
it has lots of set methods and all of them return number
I think almost nobody uses it

https://hegel.js.org/try#MYewdgzgLgBAJgQygUxgXhmZB3GARJZACgEoAoRFAOgmSgAkQBXAJwiIEYAmEoA

[thecotne]

i think sooner or later we need to introduce strictness rules and/or warnings

so if someone does not mind prepending void to bunch of statements and they can opt-in (or opt-out whatever)
i think opt-out option is better so that it's strict by default and you turn off some checks if it gets annoying ...

also it's good for education purposes to have checker complain about unused values and to discover that some functions actually have return values (and you will be like "So interesting this tool is pretty cool!")

[srg-kostyrko]

I created PR that fixes most of places
there are couple point where array.push is used - I have not changed them for now

other point is about type inference
https://hegel.js.org/try#GYVwdgxgLglg9mABAZwKZRABwKICZsAUAJgEYCUiA3gFCKKkB0ATqhAmK1AWQNzUC+1IA
not sure though that we should change it in this case

[JSMonk]

I've merged. Thank you a lot ^_^.