4 ms·

s/strong/static/

• carlob 13y ago
  You're right, but Haskell is also statically typed and can be compiled, so my question still holds.
  • untothebreach 13y ago
    Rather than saying that Haskell solves this with the `Either` type, I believe it is more accurate to say that in this case, the return value of `random.choice` would be a "sum type." But the actual type would be dependent on the value passed to `random.choice`.
    • exDM69 13y ago
      No, using the Either type wouldn't be the same at all. Yes, you can do choice [Left "foo", Right 42] (from Data.Arbitrary, used by QuickCheck) but it's not really the same thing. The two elements in the list both have the type Either String Int, unlike the Python example. Further, an Either can have only two possible kinds of values (but no-one prevents you from writing data Either3 a b c = Left a | Middle b | Right c). You can achieve something like this with type classes, though. This is somewhat similar to requiring all the elements to fullfill an interface, kind of like List<Comparable> in Java-like languages. With existential quantification (there are other options) you can make a list where every element in a list can be of a different type as long as they derive from the same type class (like Eq, Ord, etc). The type class is still a constraint that Python doesn't have but it makes static typing possible. See the heterogenous collection link above.