Is it proper/ok to defines them as : fromIntegral :: (a::Integral) -> (b::Num) and round :: (a::RealFrac) -> (b::Integral) ?
No; Integral, Num and RealFrac are type classes, not types. Think of a type class as a "set of types" which all support certain operations. For example, anything in the Num class must implement +, -, *, and a few other things. So a type signature like (Integral a) => a means "any type a, as long as it is in the type class Integral". Is RealFrac is-a Num ? Yes, any type which is in the RealFrac type class must also be in the Num type class. Does the order matters in (Num b,Integral a) => a -> b or
(Integral a,Num b) => a -> b
No, the order of type class constraints doesn't matter. With your encouragements, I'll keep pluuging. Thanks. Good luck! -Brent