G'day all.
Quoting alex <[EMAIL PROTECTED]>:
I would like to do this:
class Foo t where
hi :: t -> Bool
class Foo t => Bar t where
hi x = True
This is arguably one of the most requested features in Haskell. The only
reason why it hasn't been implemented yet is that some of the corner cases
are a little subtle.
But this will get fixed, won't it, haskell-prime people?
What you'll have to do until then is something like this:
class Num a => Alg a where
(<>) :: Mat m => m -> a -> a
multByVec :: (Vec v, Mat m) => m -> a -> a
multByVec m v = fromColumn (m <> toColumn v)
class Alg v => Vec v where
toRow, toColumn :: Mat m => v -> m
fromRow, fromColumn :: Mat m => m -> v
fromRow = fromColumn . transpose
toRow = transpose . toColumn
class Alg m => Mat m where
transpose :: m -> m
class Alg SomeType where
(<>) = multByVec
class Vec SomeType where
toRow = {- etc etc -}
{- and so on -}
Sorry, I wish there was a better answer.
Cheers,
Andrew Bromage
_______________________________________________
Haskell-Cafe mailing list
[email protected]
http://www.haskell.org/mailman/listinfo/haskell-cafe
