feat: Add array length function, closes #3308

[peternewman]

Should this be targeted at main or develop?

Happy to hear other name suggestions, I've mirrored strlen for now.

I did wonder should I add push/pop at the same time (and possibly others...)

[dnmeid]

Here are my thoughts:
I think the name of strlen() is dated back to the time when variables had always and ever been strings and was chosen to make that more clear. I would keep strlen for legacy reasons and add a new generic function length(). That function length should work with strings (number of unicode graphemes), arrays (number of elements), JSON (number of properties). It could also work for integer numbers by returning the length of the string representation. We can then extend this if we introduce e.g. enums in the future.

As it is a feature that I think will not need super heaviy testing it should be targeted at main.

Feel free to add more useful functions.

Please write a little less minimalistic description in the getting started. Especially examples are very useful and the description needs to be suitable for non programmers. If you say a function "lenght" gives the lenght, that is not super useful. You need to explain more basic, like "count of elements".

[dnmeid]

@peternewman still there?

[peternewman]

Here are my thoughts: I think the name of strlen() is dated back to the time when variables had always and ever been strings and was chosen to make that more clear. I would keep strlen for legacy reasons and add a new generic function length(). That function length should work with strings (number of unicode graphemes), arrays (number of elements), JSON (number of properties). It could also work for integer numbers by returning the length of the string representation. We can then extend this if we introduce e.g. enums in the future.

That sounds very sensible, I'll pivot to that.

As it is a feature that I think will not need super heaviy testing it should be targeted at main.

Great, I'll leave this targeted as is then.

Feel free to add more useful functions.

I realised pop would need to return both the modified array (or modify it in place) and the item that was popped, I'm not aware of other functions working like that currently. Obviously push would be pretty easy.

Please write a little less minimalistic description in the getting started. Especially examples are very useful and the description needs to be suitable for non programmers. If you say a function "lenght" gives the lenght, that is not super useful. You need to explain more basic, like "count of elements".

Sorry, lazy copy/paste of the strlen thing.

@peternewman still there?

Yeah sorry, just competing open source stuff and other commitments.

[dnmeid]

expect(ExpressionFunctions.length('ä')).toBe(1) // codepoint U+00E4, one grapheme
expect(ExpressionFunctions.length('̈a')).toBe(1) // codepoints U+0308 U+0061, one grapheme
expect(ExpressionFunctions.length('́̈a')).toBe(1) // codepoints U+0301 U+0308 U+0061, one grapheme

[peternewman]

Seems this is pretty hard to do entirely properly, but do you think of these is "good enough"?
https://mathiasbynens.be/notes/javascript-unicode

[dnmeid]

Actually node.js has the Intl.segmenter() since version 16 but that is not working 100% with combining marks.
https://www.npmjs.com/package/unicode-segmenter should do the trick and is even faster than the built in Intl.segmenter()

[dnmeid]

Not all uncatched types have a lenght property, e.g. BIGINT

[peternewman]

I've added BigInt. What others are you aware (RegExp maybe) of/what do you think I should do in the default case?

[peternewman]

Added RegExp too now...

[dnmeid]

Hm, I think string should have its own case and then it is not part of the unknown rest any more. The unknown rest could maybe return NaN.
From the JS perspective there are also iterators and generators that are interesting for length() but currently we don't use them in variables, so if you want to implement them it would be a bonus for possible future use. Also we don't use regex data type currently and I'm not sure about the value of knowing the length of a regex.