KC
From a more technical point of view, what 'Just' does is wrapping data. Whenever you see 'Just', keep in mind you're looking at a data constructor.
Would it be more correct to say that "Just" wraps a pure value?
That would be misleading. First of all, think in terms of Maybe, not in terms of Just. "Just 3" is a value of type Maybe Integer just like "True" is a value of type Bool. There is really nothing special about it. Think of Maybe as a list type, which can contain at most one element. In that sense [] corresponds Nothing and [3] corresponds to Just 3. You can pattern-match against both of them in the same way: case maybeValue of Nothing -> "We got nothing." Just _ -> "We got a value." case listValue of [] -> "We got nothing." [_] -> "We got one value." [_,_] -> "We got two values." _ -> "We got more than two values." So why is it misleading? Because (not considering that everything is pure in Haskell) there is nothing impure about Maybe. Greets, Ertugrul -- nightmare = unsafePerformIO (getWrongWife >>= sex) http://ertes.de/