Combinators for functions in Gen

[kevin-lee]

Current Gen does not have combinators for functions (e.g. Gen[A => B]).
There are some cases where having function combinators is really handy (e.g. Functor laws, Monad laws, etc.) so can we have function combinators maybe like Gen.function1, Gen.function2, etc.?

As you know, there is a function generation project for Haskell Hedgehog.
http://hackage.haskell.org/package/hedgehog-fn
https://github.com/qfpl/hedgehog-fn