On Tue, Nov 18, 2008 at 02:18:46PM -0800, Michael Snoyman wrote:
Very interesting solution to the problem. I tried it out and it works perfectly... but it's just too much of a hack for my tastes (no offense; I
None taken. =)
class RepTuple a b | a -> b where toList :: a -> [b] tMap :: (b -> b) -> a -> a
instance RepTuple (a, a) a where toList (a, b) = [a, b] tMap f (a, b) = (f a, f b)
And so on and so forth for every kind of tuple. Of course, this runs into the issue of the single case, for which I used the OneTuple library (actually, I wrote my own right now, but I intend to just use the OneTuple library).
This is reasonable too. It's just a tradeoff of hackishness vs. code length/tediousness. I.e. in the solution with type-level naturals, you don't need a separate instance like this for every number you're going to use. And no one really likes writing things like tMap f (a,b,c,d,e,g,h,i,j) = ... =) -Brent