NAME
    head - create a list of specified size from the head of a list

SYNOPSIS
    head(x, y)

TYPES
    x		list
    y		int

    return	list

DESCRIPTION
    If 0 <= y <= size(x), head(x,y) returns a list of size y whose
    elements in succession have values x[[0]]. x[[1]], ..., x[[y - 1]].

    If y > size(x), head(x,y) is a copy of x.

    If -size(x) < y < 0, head(x,y) returns a list of size (size(x) + y)
    whose elements in succession have values x[[0]]. x[[1]], ...,
    i.e. a copy of x from which the last -y members have been deleted.

    If y <= -size(x), head(x,y) returns a list with no members.

    For any integer y, x == join(head(x,y), tail(x,-y)).

EXAMPLE
    > A = list(2, 3, 5, 7, 11)
    > head(A, 2)

    list (2 members, 2 nonzero):
	  [[0]] = 2
	  [[1]] = 3

    > head(A, -2)

    list (3 members, 3 nonzero):
	  [[0]] = 2
	  [[1]] = 3
	  [[2]] = 5

LIMITS
    none

LIBRARY
    none

SEE ALSO
    tail, segment