Simplify the representation of the Free monad.

[runarorama]

Review by @pchiusano, @vmarquez, @divarvel, and/or @aloiscochard appreciated.

[runarorama]

I am a little displeased that x and x.flatMap(pure) don't have the same in-memory representation or the same performance characteristics. A user cannot observe the difference other than with timing, but it seems less than ideal.

Note that this implementation does no walking under Gosubs in flatMap. We have to eat the cost of reassociating binds sooner or later, and here we're opting for later.

[tpolecat]

Would be nice to see this reworked rather than deleted. People seemed to find it helpful.

[jedws]

lgtm

[japgolly]

Value is lazy here but eager in Return.

[aloiscochard]

That is great!

Less is more, I think it makes thing much easier to understand to anyone diving in the code now that there is just a single implementation.

Plus, I was never very comfortable with that arbitrary 500 limit :-)

About the sub-optimal performance concerns of x.flatMap(pure), well it's Scala... personally, I think the trade-off is worth it due to the big abstraction benefit we can see here.

LGTM

[vmarquez]

Looks good.