(guess who finally decided to learn about imp params :P)
this looks like a bug to me, but of course i may be wrong.
consider these definitions:
> data BLSupply = BLSupply [Bool]
>
> instance Splittable BLSupply where
> split (BLSupply l) = (BLSupply (True:l), BLSupply (False:l))
>
> newBL (BLSupply bl) = bl
basically we can name things by lists of bools
we name lists using this function:
> number :: (%ns :: BLSupply) => [a] -> [(a,[Bool])]
> number [] = []
> number (x:xs) = (x,n) : number xs
> where n = newBL %ns
which works fine. in ghci:
*ImpParam> let %ns = BLSupply [] in number "hello"
[('h',[False]),('e',[False,True]),('l',[False,True,True]),('l',[False,True,True,True]),('o',[False,True,True,True,True])]
Whee. now here's the wierd thing. suppose we remove the type signature
from the number function. then, in ghci:
*ImpParam> :t number
forall a. (%ns :: BLSupply) => [a] -> [(a, [Bool])]
*ImpParam> let %ns = BLSupply [] in number "hello"
[('h',[]),('e',[]),('l',[]),('l',[]),('o',[])]
what gives? why did it suddenly break even though it gets the type right?
- hal
--
Hal Daume III
"Computer science is no more about computers | [EMAIL PROTECTED]
than astronomy is about telescopes." -Dijkstra | www.isi.edu/~hdaume
_______________________________________________
Glasgow-haskell-users mailing list
[EMAIL PROTECTED]
http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
