Tests

atom(X)

Succeed if X is an atom (an empty list is considered an atom).

atomic(X)

Succeed if X is an atom or number.

number(X)

Succeed if X is a number.

integer(X)

Succeed if X is an integer.

float(X)

Succeed if X is a real number.

var(X)

Succeed if X is unbound (a non-instantiated variable).

nonvar(X)

Succeed if X is bound.

X == Y

Succeed if X and Y are identical (but do not unify them).

X \== Y

Succeed if X and Y are not identical.

[End]