Collections come as lists, records and tuples. One way they differ is that collections in Elm are always immutable.
Lists represent arrays,
Records represent objects and
Tuples represent collections of varying size (whose elements share a consistent type). Tuples are record-like but can only be accessed by position.
-- Destructuring a tuple multiply3d (x,y,z) = x * y * z multiply3d (1,2,3)