On Mon, 2008-09-29 at 20:02 -0700, Jason Dagit wrote: > Hello, > > I recently had someone point me to this thread on LtU: > http://lambda-the-ultimate.org/node/2003 > > The main paper in the article is this one: > http://www.jucs.org/jucs_10_7/total_functional_programming/jucs_10_07_0751_0768_turner.pdf > > It leaves me with several questions: > 1) Are there are existing Haskell-ish implementations of the total > functional paradigm? > 2) Could we restructure Haskell so that it comes in 3 layers, total > functional core, lazy pure partial functional middle, and IO outer > layer? > > The idea with #2 is that similar to how we use the type system to > separate the purely functional from monadic, and in particular IO > actions, can we make the inner most part of Haskell total? > Furthermore, could we do this in a way that makes it easy to > intermingle the three layers the way we can mingle pure Haskell with > IO actions? > > Maybe instead of using (->) as the function constructor for total > functions we use a different symbol, say (|->), and the compiler knows > to use the more specialized semantics on those definitions. I'm not > sure how make this work for values that are total functional versus > values that are just pure (partial) functional.
This can be done exactly the same way it is done with IO. Remove general recursion* from Haskell and have a partiality monad with fix :: (a -> a) -> Partial a This particular idea has been discussed several times in a couple of places. Most people seem to think it would be too much of a hassle to use. * and other stuff, but that's the significant one, it's easy enough to add a primitive error :: String -> Partial a _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
