Pair Types

A pair has two values, a first and rest. You can create a pair like this:

let pair = (42, 34);

Lists

Pairs can be nested arbitrarily:

let chain = (100, (200, (300, nil)));

In fact, the above structure is identical to a nil-terminated list with those items.

let chain = [100, 200, 300];

These both have the following type:

(Int, (Int, (Int, nil)))

Which can be assigned to the recursive type List<Int>.