Module Stdlib320.List

length l is the number of elements in l

let _ = assert (length [1;2;3] = 3)

nth l i is the ith element of l if i >= 0 and i < length l

let _ = assert (nth [1;2;3] 1 = 2)

Raises a Failure exception if length l < i and an Invalid_argument exception if i < 0

Same as the previous function, but is None in the case of failure.

Reverses a list

let _ = assert ([rev [1;2;3] = [3;2;1]])

Combines a list of lists from left to right

let _ = assert ([concat [[1;2;3];[4;5;6];[7;8;9]] = [1;2;3;4;5;6;7;8;9]])

map f l is l but with f applied to every element

let _ = assert (map abs [-1;-2;-3] = [1;2;3])

filter f l is the elements of l (in order) which satisfy the predicate f

let _ = assert ([filter ((<) 5) [3;4;5;6;7] = [6;7]])

Left-associative folding function for lists. fold_left op init [x_1;x_2;...;x_n] is equivalent to op (...(op (op init x_1) x_2)...) x_n

Right-associative folding function for lists. fold_right op [x_1;x_2;...;x_n] is equivalent to op x_1 (op x_2 (...(op x_n base)...))

Membership predicate for lists. mem x l is

• true if x appears in l
• false otherwise

Finds based on a predicate. find f l is the first appearance of an element of l which satisfies f.

Raises a Not_found exception otherwise.

Same as the previous function, but is None in the case of failure.

Generic sorting function for lists. sort f l has the same elements as l, but sorted according to the comparing function f

Membership function for association lists. assoc x l is equivalent to

snd (find (fun (k, v) -> k = x))

Same as the previous function, but is None in the case of failure

remove_assoc k l is l but with the first appearance of a pair of the form (k, v) removed