| Both GHC and Hugs have a bug in their Prelude for Ratio's Enum
| instance. The following program
|
| import Ratio
| main = print [ 1, 4%(3::Int) .. 2 ]
|
| should print
|
| [1 % 1,4 % 3,5 % 3,2 % 1]
|
| but instead an infinite list of 1%1s is generated. The reason for this
| is that the default method for enumFromThenTo is used, which truncates
| 4%3 to 1 (same for enumFromTo).
| Malcolm Wallace wrote:
| > I'd say that this is a bug in the Library Report, which seems to
| > specify this implementation. [...]
|
| But for Float, Double, Ratio and friends the report explicitly
| states that numericEnumFromFooBar has to be used, which generates
| the finite list. So it's only a bug in all implementations. >:-)
Indeed, GHC's libraries are wrong. We'll fix that.
I don't propose to change the H98 defn of Enum instances though,
flawed though they may be.
Simon
