insert : 'a -> 'a list -> 'a list

SYNOPSIS
Adds element to the head of a list if not already present.

DESCRIPTION
The call insert x l returns just l if x is already in the list, and otherwise returns x::l.

EXAMPLE
  # insert 5 (1--10);;
  val it : int list = [1; 2; 3; 4; 5; 6; 7; 8; 9; 10]
  # insert 15 (1--10);;
  val it : int list = [15; 1; 2; 3; 4; 5; 6; 7; 8; 9; 10]

USES
An analog to the basic list constructor :: but treating the list more like a set.

SEE ALSO
union, intersect, subtract.