It's possible to augment Haskell type system to be the one in Epigram. But it would no longer be Haskell. :) And to meet the goals of Epigram you'd also have to remove (unrestricted) recursion from Haskell. -- Lennart On Dec 21, 2006, at 23:46 , Brian Hulley wrote:
Jacques Carette wrote:
Yes, dependent types have a lot to do with all this. And I am an eager lurker of all this Epigram.
Would it be possible to augment Haskell's type system so that it was the same as that used in Epigram? Epigram itself uses a novel 2d layout and a novel way of writing programs (by creating a proof interactively) but these seem orthogonal to the actual type system itself.
Also, typing is not the only issue for compile time guarantees. Consider:
data Dir = Left | Right | Up | Down deriving Eq
-- Compiler can check the function is total foo :: Dir -> String foo Left = "Horizontal" foo Right = "Horizontal" foo Up = "Vertical" foo Down = "Vertical"
versus
-- Less verbose but compiler can't look inside guards foo x | x == Left || x == Right = "Horizontal" foo x | x == Up || x == Down = "Vertical"
versus something like:
foo (Left || Right) = ... foo (Up || Down) = ...
Brian. -- http://www.metamilk.com _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe