Repeatedly func

[EncodePanda]

repeatedly returns one more time a function value (instead of being a method).

also added ginterpret

[CLAassistant]

All committers have signed the CLA.

[sellout]

I would like this to be a function, but the problem is that we need this to be tail recursive.

We could actually rewrite this as a coalgebra, like:

final def repeatedlyƒ[A](f: A => Option[A]): Coalgebra[A \/ ?, A] = f(expr) \/> expr

final def repeatedly[A](f: A => Option[A]): A => A =
  _.ana[Nu](repeatedlyƒ(f)).unsafePerformSync

We have some stack-safety tests of Partial that make me think this works, although no performance promises.

But then maybe we can rewrite stuff to use repeatedlyƒ instead of repeatedly, and track partiality through more of the code.

@edmundnoble – thoughts?

[sellout]

👍🏾

[sellout]

So, Matryoshka has a new definition of repeatedly now that basically requires it to return Partial[A], tracking the general recursion explicitly, so if this PR (including the description) could be updated to only have ginterpret in it, that’d be great, and we can get it merged and gone.

[EncodePanda]

👍 but Monday after spark summit

[sellout]

@rabbitonweb Ping.