Hi all,
This is my first post to haskell-beginners. I am trying to use the
SegmentTree-0.2 library from Hackage but I get an error when I try to
use some of its functions. For instance when I load a file containing
the following
module Stabbing.SegmentTree (counts) where
import Data.SegmentTree
counts :: [(Rational, Rational)] -> [Rational] -> [Integer]
counts intervals points = map (countingQuery segmentTree) points
where
segmentTree = fromList intervals
in the GHC interpreter (6.10.3), my interactions look as such
*Stabbing.SegmentTree> counts [(4, 5)] [3]
[0]
*Stabbing.SegmentTree> fromList [(4, 5)]
<interactive>:1:0:
No instance for (SegmentTree-0.2:Data.SegmentTree.Measured.Measured
(SegmentTree-0.2:Data.SegmentTree.Interval.Interval t) t1)
arising from a use of `fromList' at <interactive>:1:0-16
Possible fix:
add an instance declaration for
(SegmentTree-0.2:Data.SegmentTree.Measured.Measured
(SegmentTree-0.2:Data.SegmentTree.Interval.Interval t) t1)
In the expression: fromList [(4, 5)]
In the definition of `it': it = fromList [(4, 5)]
As you can see, "fromList intervals" is a sub-expression of counts,
but when I try to evaluate a similar expression at the interpreter, I
get an error. Does anyone know what the problem is? This is not the
"No instance for (Show ..." error that I'm used to.
Ogechi Nnadi.
