On Mon, 2013-04-29 at 20:19 +0200, Gábor Lehel wrote:
Thanks for the explanation. I looked at your thesis previously, but only read through a couple of sections (including the one about concatMap). I might go through the state machine parts as well now that I know the significance/relevance.
The thing in particular that was motivating me is that if it weren't for Skip, it seems that to some extent (I haven't had time to investigate precisely what extent) you could write a stream fusion framework in a datatype-generic way, parameterized over the base functor. But it wasn't obvious to me how (or whether) you would translate Skip. But maybe the state machine perspective will provide some insight into that. I'll think about it.
Oh I think you can write it in a data-type generic way. If your datatype is described by a base functor F, then the skip version is a simple transformation on that functor. F_skip a = F a + a And then the stream type for F is nu a. F_skip a See section 3.6. In most of my theory chapter I write it in this style, rather than using the list functor specifically. Duncan