4.8.10 Summary of Predicates

atom(+T) ISO

term T is an atom

atomic(+T) ISO

term T is an atom or a number

callable(+T)

T is an atom or a compound term

compound(+T) ISO

T is a compound term

float(+N) ISO

N is a floating-point number

ground(+T)

term T is a nonvar, and all substructures are nonvar

integer(+T) ISO

term T is an integer

mutable(+X)

X is currently instantiated to a mutable term.

nonvar(+T) ISO

term T is one of atom, number, compound (that is, T is instantiated)

number(+N) ISO

N is an integer or a float

simple(+T)

T is not a compound term; it is either atomic or a var

var(+T) ISO

term T is a variable (that is, T is uninstantiated)

compare(-C,+X,+Y) meta-predicate

C is the result of comparing terms X and Y

+X == +Y ISO

terms X and Y are strictly identical

+X \== +Y ISO

terms X and Y are not strictly identical

+X @< +Y ISO

term X precedes term Y in standard order for terms

+X @>= +Y ISO

term X follows or is identical to term Y in standard order for terms

+X @> +Y ISO

term X follows term Y in standard order for terms

+X @=< +Y ISO

term X precedes or is identical to term Y in standard order for terms

?T =.. ?L ISO

the functor and arguments of term T comprise the list L

?X = ?Y ISO

terms X and Y are unified

+X \= +Y ISO

terms X and Y no not unify

?=(+X,+Y)

X and Y are either strictly identical or do not unify

arg(+N,+T,-A) ISO

the Nth argument of term T is A

atom_chars(?A,?L) ISO

A is the atom containing the character atoms in list L

atom_codes(?A,?L) ISO

A is the atom containing the characters in code-list L

atom_concat(?Atom1,?Atom2,?Atom12) ISO

Atom Atom1 concatenated with Atom2 gives Atom12.

atom_length(+Atom,-Length) ISO

Length is the number of characters of the atom Atom.

char_code(?Char,?Code) ISO

Code is the character code of the one-char atom Char.

copy_term(+T,-C) ISO

C is a copy of T in which all variables have been replaced by new variables

copy_term(+T,-C,-G)

C is a copy of T in which all variables have been replaced by new variables, and G is a goal for reinstating any attributes in C

create_mutable(+Datum,-Mutable)

Mutable is a new mutable term with current value Datum.

dif(+X,+Y)

X and Y are constrained to be different.

frozen(+Var,-Goal)

The goal Goal is blocked on the variable Var.

functor(?T,?F,?N) ISO

the principal functor of term T has name F and arity N

get_mutable(-Datum,+Mutable)

The current value of the mutable term Mutable is Datum.

name(?A,?L)

the code-list of atom or number A is L

number_chars(?N,?L) ISO

N is the numeric representation of list of character atoms L

number_codes(?N,?L) ISO

N is the numeric representation of code-list L

numbervars(+T,+M,-N)

number the variables in term T from M to N-1

sub_atom(+Atom,?Before,?Length,?After,?SubAtom) ISO

The characters of SubAtom form a sublist of the characters of Atom, such that the number of characters preceding SubAtom is Before, the number of characters after SubAtom is After, and the length of SubAtom is Length.

unify_with_occurs_check(?X, ?Y) ISO

True if X and Y unify to a finite (acyclic) term.

?T =.. ?L ISO

the functor and arguments of term T comprise the list L

append(?A,?B,?C)

the list C is the concatenation of lists A and B

keysort(+L,-S)

the list L sorted by key yields S

length(?L,?N)

the length of list L is N

member(?X,?L)

X is a member of L

memberchk(+X,+L)

X is a member of L

nonmember(+X,+L)

X is not a member of L

sort(+L,-S)

sorting the list L into order yields S