Hi, Is there any development effort to create a Haskell interpreter/compiler/sublanguage that is annotated? For instance, I might be able to say something like:
sortByF f = sortBy (\a b -> compare (f a) (f b))
longest [] = error "longest on empty list" longest (x:xs) = longest' xs (length x) where longest' [] len = len longest' (x:xs) len | length x > len = longest' xs (length x) | otherwise = longest' xs len
x = sortByF length (a long list of lists) y = sortByF (longest y - . length) (another long list of lists)
obviously x will evaluate properly and will sort it's list by length. y, whose intention is basically to sort by reverse length (yes, I know there are other ways to doing this), will error with "Loop" for obvious reasons. however, intuitively, we all know that the sorting of y doesn't affect the length of the longest element therein. is there any language extension that allows you to make these annotates in the definitions of longest and sortByF that would enable this definition of y to not produce an error? thanks! - hal -- Hal Daume III "Computer science is no more about computers | hdaume@isi.edu than astronomy is about telescopes." -Dijkstra | www.isi.edu/~hdaume