cadr, caddr, cadddr, caddddr, first … fifth

Syntax: (cadr PAIR), (caddr PAIR), (cadddr PAIR), (caddddr PAIR); (first PAIR) through (fifth PAIR)

Behaviour: cadr through caddddr are macros that expand to nested car and cdr: cadr is the second element, caddr the third, and so on. Being macros, they expand in call position even when a local binding of the same name exists. Each also has a runtime function binding of the same name, so cadr can be handed to a higher-order function as a value.

first through fifth are runtime bindings only – car, cadr, caddr, cadddr, and caddddr as functions. They resolve as ordinary values, so a local binding of the same name shadows them in call position.

Examples:

>>> (cadr '(1 2 3))
2
>>> (third '(1 2 3))
3
>>> (fifth '(1 2 3 4 5))
5
>>> (list (map first #['(1 2) '(3 4)]))
#[1 3]

>>> (let [[first (lambda [p] "shadowed")]] (first '(1 2 3)))
"shadowed"
>>> (let [[cadr (lambda [p] "shadowed")]] (cadr '(1 2 3)))
2

See also: car, cdr, Data structures.

Also: function caddddr, cadr, fifth, first.