List

The list namespace includes several common list-manipulating predicates.

• pred append ([A],[A],[A])
  mode append (in,in,out)
  mode append (out,out,in)
  Holds if the third argument is the result of appending the first two arguments.
• pred mem(A,[A])
  mode mem(out,in)
  Holds if the first element is an element of the second.
• pred concat([[A]],[A])
  mode concat(in,out)
  Holds if the second list is the result of concatenating all the elements of the first list.
• pred remove(A,[A],[A])
  mode remove(in,in,out)
  Removes all occurrences of the first argument from the second and returns the result as the third.

• pred reverse([A],[A])
  mode reverse(in,out)
  Holds if the first list is the reverse of the second (and vice versa).