pick function about purescript-record

[MonoidMusician]

This looks useful to me!

Regarding your implementation, it would probably be best to implement it in FFI for performance reasons (as unsafePick or something in the Unsafe module).

Oops, commented too early.

But I would also suggest using RProxy r instead of Proxy (Record r), just because you aren't doing anything with the information that it's a record inside the proxy ...

Otherwise it looks good to me, nice suggestion!

[MonoidMusician]

Confession: I was originally going to suggest using something like insert/delete, then I realized that wouldn't be any better, hence FFI. My other bad idea was to implement delete in terms of pick 😁 But your PR looks good to me!

[paf31]

It would need to use the FFI anyway, since I don't really want to add a maps dependency here.

What are the use cases for this?

[coot]

In Redux when you connect a component to a state, and you want to match what you need as tight as possible (which is an optimisation).

Another case how I am using it is when using css-modules and importing css into purescritp through ffi:

foregin import css :: { header :: String, section :: String, footer :: String }

But then a component might just require a section of those css classes.

Sure ffi is the way to go, it's just not accessible in try.purescript :)

[coot]

I guess the right place for the class SubRow is in Type.Row. I'll submit a PR there too.

[coot]

The only dependency that this will introduce is for Data.Array, I hope it's fine. It just requires cons (the new DCE that I am working on is able to cut everything out except the required function :) )