Data.Record.Builder.modify

[joneshf]

Asked on slack, but figure it is less likely to get lost here.

I noticed there's no modify for Data.Record.Builder (akin to modify in Data.Record). Was that an intentional choice or an oversight? If an oversight, I'll submit a PR.

It might also be possible if there were a Functor instance for Builder. Would this work without breaking things? I remember we talked about adding a Profunctor instance, but it would break something. So, Functor is the next best thing, I think.

[garyb]

I would have thought it's an oversight :)

[paf31]

A Functor instance would definitely not be possible, since it would allow non-linear uses of the input argument to sneak in. Same for Profunctor.

I think modify is safe though.