Re: [Haskell-cafe] laziness blowup exercise

I played with this a bit, and ok, it seems the difference between iterate' and iterate'' is h _ = 2 tit' = head . drop 1 . iterate' h $ undefined tit'' = head . drop 1 . iterate'' h $ undefined

(Bas wishes for a type system that can express the different strictness properties of these functions...)

Is this being worked on? Could you give some example of type systems that can express differences between functions of along dimension x? Off the top of my head, I guess (?) with dependent types can tell the difference between total and partial functions... partials won't even compile, right? Are there others? Pointers appreciated.

...seems the most lazy strict iterate.

could you expand on what you mean by this? 2009/7/16 Bas van Dijk :

On Wed, Jul 15, 2009 at 6:35 PM, Ryan Ingram wrote:

...

iterate' f x = x `seq` x : iterate' f (f x) seems better; it doesn't evaluate list elements you don't visit.

iterate'' f x = x : (iterate'' f $! f x)

...seems the most lazy strict iterate.

(Bas wishes for a type system that can express the different strictness properties of these functions...)