The problem I see is that in both: Version: September 2006 of hugs, which is the one that is current for Ubuntu 9.10 release, and ghci 6.10.4, they both exhibit a {I think} strange behaviour, in regards to the shorthand way of calling out a list of enumerable values. I will explain the problem that I have run into with examples: Hugs> [3,7..22] [3,7,11,15,19] <- OK Hugs> map (* 1.0) [3,7,11,15,19] <- manual spec OK [3.0,7.0,11.0,15.0,19.0] Hugs> map (* 1.0) [3,7..22] <- same spec as first but !!! when mapped to with a (*1.0) to coerce them to reals: [3.0,7.0,11.0,15.0,19.0,23.0] <- went one outside of range spec. ======================================== Exactly the same behaviour from ghci 6.10.4 : Prelude> [3,7..22] [3,7,11,15,19] Prelude> map (* 1.0) [3,7..22] <- using a range [3.0,7.0,11.0,15.0,19.0,23.0] <- it screws up {at least it is not a "feature' to me} Prelude> map (* 1.0) [3,7,11,15,19] <- spelled out it acts "right". [3.0,7.0,11.0,15.0,19.0] This seems like a possible bug? or at least a sure fire trap waiting to be sprung ... one of those nasties that could really create havoc if someone is not aware of this behaviour and buries a function that include something that unwittingly coerces from an Integral to a Realfrac or Fractional. Is this a well known thing to watch out for.. or is it something that can be worked around, other then having to enumerate every value in a list rather then use the handiness of the range notation as shorthand? cheers, gene