.indexed(), .reread(), .rewrite()

[akheron]

No description provided.

[akheron]

@merisbahti FYI

[merisbahti]

Hello Petri, thank you for this, very interesting with the reread and rewrite optics.

I've reimplemented klyva's todo example using "pure" optics now:
merisbahti/klyva@ec20eea

The changes were:

1. Add indexed() optic before filter optic, this results in an Atom<Array<[number, Todo]>> (previously Atom<Array<Todo>>.
2. Use useAtomSlice to slice atom, into an Array<Atom<...>> instead.
3. Map this sliced atom and pass todoAtom prop, but use the nth-optic to focus on the 2nd element in the [index, Todo]-tuple:

              todoAtom={focusAtom(todoAtom, optic => optic.nth(1))}

2 questions:
This seems to work without the rewrite sort lens, thought it would be needed?
Have I done it correctly?

[merisbahti]

This seems to work without the rewrite sort lens, thought it would be needed?

Oh, yes, after reading the docs this is mentioned that it's being done automatically. Cool. Thanks.

[akheron]

Yeah, the thing is that if you want to use O.remove() you have to target an element of the [index, value] array instead of the 2nd element of the tuple, which is not removable. But yeah, the sorting that is applied when writing through indexed handles the rest nicely.