With GHC-5.02.2, I do
$ ghci
Prelude> :m Ratio
Ratio> [1%2..10%2]
[1 % 2,3 % 2,5 % 2,7 % 2,9 % 2,11 % 2]
The question is, why is there 11%2 at the end of the list?
It's inconsistent with the (good) rules for Integer, since
Ratio> [1,3..10]
[1,3,5,7,9]
Is this intentional?
Feri.