Recursive objectLens

[raimohanska]

Would you like a recursive objectLens, so U could

Lens.objectLens("author.firstName")(book).set("brian")

? I'll PR, if this makes sense to you...

[puffnfresh]

Yes, I definitely want something like this - but not on objectLens, which should be handle all properties (yes, even silly ones with dots or unicode).

Something like this would be cool:

Lens.parse('author.0.firstName')
// non-integral become objectLens
// integral become arrayLens

And maybe another:

Lens.fromArray(['author', 0, 'firstName'])
// typeof x == 'string' become objectLens
// typeof x == 'number' become arrayLens

And they should of course have appropriate PartialLens versions.

[raimohanska]

I see. You want to cover all the bases. Not the easy-going javascripter, this one :) But yeah, you're probably right.

However, from the API user's point of view, I don't like parse too much. As a user I'm don't want to think about parsing, but object fields instead. Actually I'd prefer

Lens("author.firstName")(book).set("brian")

The Lens constructor could provide a super-easy way for constructing lenses from strings and maybe function, function pairs in the spirit of the Facade pattern. Then you'd have a more strict API in the form of Lens.X, Lens.Y constructors.

[Freyert]

Out of curiosity, why the differentiation between Array and Object lenses?

[SimonRichardson]

I wrote this ages ago and covers the original idea: https://github.com/SimonRichardson/fantasy-lenses/blob/master/lens.js#L103