Testing Prolog terms

The following functions are provided for testing Prolog terms. They return 1, meaning a success, or 0, meaning a failure.

• int is_ATOM(TERM t) Term t is an atom.

• int is_INTEGER(TERM t) Term t is an integer.

• int is_FLOAT(TERM t) Term t is a floating-point number.

• int is_NIL(TERM t) Term t is a nil.

• int is_LIST(TERM t) Term t is a list.

• int is_STRUCTURE(TERM t) Term t is a structure (but not a list).

• int is_COMPOUND(TERM t) True if either is_LIST(t) or is_STRUCTURE(t) is true.

• int is_UNIFIABLE(TERM t1, TERM t2) t1 and t2 are unifiable. This is equivalent to the Prolog call not(not(t1=t2)).

• int is_IDENTICAL(TERM t1, TERM t2) t1 and t2 are identical. This function is equivalent to the Prolog call t1==t2.