[Haskell-cafe] A Random Question

What do you need, i.e., what meaning do you attribute to the words "predictable" and "arbitrary"?

Apologies - I didn't explain my problem clearly. I want to say something like: instance Arbitrary Foo where arbitrary = choose (Foo 1, Foo 5) but the "random" values are generated by my own random number generator not the standard one. Does that make sense? The reason I'm trying to do this is I am generating random test data but some of it needs to be predictable.