[Haskell-cafe] Stream fusion for Hackage

[Ross Paterson]

On Tue, Nov 20, 2007 at 07:25:08PM +1100, Roman Leshchinskiy wrote:
> Ross Paterson wrote:
>> I was saying that your "streams" are themselves coinductive objects.
>> Is that controversial?
>
> They aren't recursive so in my view, they themselves are just as 
> (co)inductive as, say, a function of type (a -> a).

To quote your own paper, "stream fusion uses an explicit representation
of the sequence co-structure [or unfolding]: the Stream type."  The key
property of System F encodings is that they encode a recursive type in a
non-recursive form, and Stream (ignoring Skip) is the standard System F
encoding of co-inductive lists.