Re: [Haskell-cafe] laziness blowup exercise

On Thu, Jul 16, 2009 at 9:57 PM, Ryan Ingram wrote:

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On Thu, Jul 16, 2009 at 8:22 PM, Thomas Hartman wrote:

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Is this being worked on?

On Thu, Jul 16, 2009 at 12:35 PM, Bas van Dijk wrote:

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I have no idea.

Yes.

Bolingbroke, Peyton-Jones.  "Types are calling conventions" http://lambda-the-ultimate.org/node/3319

Thanks for the pointer to this interesting paper! However I dont't think that the type system explained in that paper is powerful enough to differentiate between these different iterates: iterate1, iterate2, iterate3, iterate4 :: (a -> a) -> a -> [a] iterate1 f x = x : let nxt = f x in iterate1 f nxt iterate2 f x = let nxt = f x in nxt `seq` x : iterate2 f nxt iterate3 f x = x `seq` x : let nxt = f x in iterate3 f nxt iterate4 f x = x : let nxt = f x in nxt `seq` iterate4 f nxt The type system somehow has to express the growing and shrinking of the stack so that it can statically disallow: iterate1 (+ 1) 0 !! (10^6) :: Int & <fits in my stack> and allow: iterate4 (+ 1) 0 !! (10^6) :: Int & <fits in my stack> Bas