Identity lists

True iff memberchk/2 is true.

Checks that X is an element of (list) Xs.

Usage:list_insert(List,Term)

Adds Term to the end of (tail-opened) List if there is not an element in List identical to Term.

• The following properties should hold at call time:
  (term_typing:var/1)List is a free variable.
  (term_typing:nonvar/1)Term is currently a term which is not a free variable.

Usage:add_after(L0,E0,E,L)

Adds element E after the first element identical to E0 (or at end) of list L0, returning in L the new list.

• The following properties should hold at call time:
  (term_typing:nonvar/1)L0 is currently a term which is not a free variable.
  (term_typing:nonvar/1)E0 is currently a term which is not a free variable.
  (term_typing:nonvar/1)E is currently a term which is not a free variable.
  (term_typing:var/1)L is a free variable.

Usage:add_before(L0,E0,E,L)

Adds element E before the first element identical to E0 (or at start) of list L0, returning in L the new list.

• The following properties should hold at call time:
  (term_typing:nonvar/1)L0 is currently a term which is not a free variable.
  (term_typing:nonvar/1)E0 is currently a term which is not a free variable.
  (term_typing:nonvar/1)E is currently a term which is not a free variable.
  (term_typing:var/1)L is a free variable.

Usage:delete(List,Element,Rest)

Rest has the same elements of List except for all the occurrences of elements identical to Element.

• The following properties should hold at call time:
  (term_typing:nonvar/1)List is currently a term which is not a free variable.
  (term_typing:nonvar/1)Element is currently a term which is not a free variable.
  (term_typing:var/1)Rest is a free variable.

Usage:subtract(Set,Set0,Difference)

Difference has the same elements of Set except those which have an identical occurrence in Set0.

• The following properties should hold at call time:
  (term_typing:nonvar/1)Set is currently a term which is not a free variable.
  (term_typing:nonvar/1)Set0 is currently a term which is not a free variable.
  (term_typing:var/1)Difference is a free variable.

Usage:union_idlists(List1,List2,List)

List has the elements which are in List1 but are not identical to an element in List2 followed by the elements in List2.

• The following properties should hold at call time:
  (term_typing:nonvar/1)List1 is currently a term which is not a free variable.
  (term_typing:nonvar/1)List2 is currently a term which is not a free variable.
  (term_typing:var/1)List is a free variable.