Arrow specification

Is there any reason not to add an Arrow specification?

https://wiki.haskell.org/Typeclassopedia#Arrow

Happy to work on it if it hasn’t been picked up before somewhere I haven’t seen.

Arrow:

Generalization of a computation a i o with input i and output o.

Given it depends on Category it will have id and compose (<<<). Then we need arr, first, second, split (aka ***) and fanout (aka &&&).

ArrowChoice

Depends on Arrow. Let us choose which arrows to execute, as opposed to all of them

Adds left, right, multiplex (aka +++), fanin (aka |||).

ArrowApply

Depends on Arrow. Let us use an arrow resulting from a previous computation in our execution path.

Adds app.

ArrowLoop

Depends on Arrow. Let us use arrows which feed output themselves, enabling recursion.

Adds loop.

[gabejohnson]

@puffnfresh Profunctor and Category are already specified. Looks like Strong needs a spec though.

[puffnfresh]

@gabejohnson Scott encode the Tuple