[RFC] Remove List and Array in favour of Dynarray

[filipeom]

I don't think the List type is being used correctly in ecma-sl. Currently, in ecmaref6, there are only 19 uses of hd and 22 uses of tl, whereas l_nth has 382 uses. Additionally, l_add has 105 uses, whereas l_prepend has only 6 uses. This indicates that we are consistently iterating over linked lists to access and add values to this type.

Alternatively, we could use the ecma-sl arrays more. However, having a fixed-size array in ecma-sl doesn't seem to be very useful, as array operations only appear to have 15 uses in total in ecmaref6.

For this reason, I think we should consider implementing Lists as dynamic arrays using the Dynarray type from OCaml 5.2 to address performance bottlenecks. Additionally, we could eliminate the Array value from ecma-sl, which is rarely used in practice.

Tagging for discussion @andreffnascimento @j3fsantos

[filipeom]

This is similar to adopting rust vectors https://doc.rust-lang.org/std/vec/struct.Vec.html

[andreffnascimento]

I've always had a problem with ECMA-SL arrays, as they rarely seemed to be used (primarily for byte operations, if memory serves me correctly??). I think there was even a point back when I stated to work in this repo where arrays weren't even accepted by the ECMA-SL parser. I'm ok with this change specially since performance is a big issue, but we should check Array/List uses within the JS standard so that we don't start deviating too much from it.

[filipeom]

I think so, arrays are so rarely used I don't even know 😅

Yeah, I'd also like to do this in a way that there is minimal impact to the current ecmaref's interpreter code so that we remain as close to the standard as possible.