6.3.6  Obtaining left and right portions of a list

The left and right commands find the left and right parts of a list. (See Section 5.2.4, Section 8.2.3, Section 6.5.1, Section 6.6.2, Section 9.3.4 and Section 9.3.5 for other uses of left and right.)

• left takes two arguments:
  • L, a list.
  • n, a positive integer.
• left(L,n) returns the first n elements of L.
• right takes two arguments:
  • L, a list.
  • n, a positive integer.
• right(L,n) returns the last n elements of L.

Examples