Mon, 25 Feb 2002 18:01:59 +0000
> I thing that wont works, look:
> contents :: IO [Char]
> parser :: Integral a => [Char] -> [a]
> control :: [Float] -> [[Float]]
> The two problems are:
> 1) The input of parser. Doesnt match with the type of input
> 2) The input of control (or the output of parser). Doesn match
> with the type of the next function.
The "do" notation used by Rijk fixes the first problem; you should try it.
For the second problem, you want to convert an Integral to a Float - but are you sure? Integers aren't floating point numbers!
If you are sure, then do something like
contents <- input "twoboxes.dat"
return (control (map fromInteger (parser contents)))
fromInteger has the type Num a => Integer -> a, and since Num Float and Integral Integer, all your type constraints will be satisfied.
Keith Wansbrough <firstname.lastname@example.org>
University of Cambridge Computer Laboratory.