Programming Languages: Concepts and Implementation

C.7 Lists

The following are some important points about lists in Haskell.

• Lists in Haskell, unlike in Scheme, are homogeneous, meaning all elements of the list must be of the same type. For instance, the list [1, 2, 3] in Haskell is homogeneous, while the list (1 "apple") in Scheme is heterogeneous.

• In a type-safe language like Haskell, the values in a tuple (Section C.8) generally have different types, but the number of elements in the tuple must be fixed. Conversely, the values of a list must all have the same type, but the number of elements in the list is not fixed.

• The semantics of lexeme [] is the empty list.

• The cons operator, which accepts an element (the head) and a list (the tail), is : (e.g., 1:2: [3]) and associates right-to-left. ...