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Yutaka Ichibangase edited this page Feb 11, 2023 · 1 revision

Welcome to the prolog wiki!

Directives

  • :- dynamic(PI) Specifies the predicates indicated by PI are dynamic. ISO
  • :- multifile(PI) Specified the predicates indicated by PI may be in multiple files. ISO
  • :- discontiguous(PI) Specifies the predicates indicated by PI may be defined by clauses which are not consecutive read-terms. ISO
  • :- op(Priority, Specifier, Op) Alters the operator table. ISO
  • :- char_conversion(In, Out) Alters the character conversion mapping. ISO
  • :- initialization(T) Registers a goal for execution right before exiting Exec() or ExecContext(). ISO
  • :- include(F) Loads the content of the file F as if it were there instead of this directive. ISO
  • :- ensure_loaded(P) Loads the content of the file P if not loaded. ISO
  • :- set_prolog_flag(Flag, Value) Alters the value for the Prolog flag. ISO

Predicates

Control constructs

  • true Always succeeds. ISO
  • fail Always fails. ISO
  • call(Goal) Calls Goal. ISO
  • ! Cut. ISO
  • P, Q Conjunction. ISO
  • P; Q Disjunction. ISO
  • If -> Then If-then. ISO
  • If -> Then; Else If-then-else. ISO
  • catch(Goal, Catcher, Recovery) Calls Goal. If an exception is raised and unifies with Catcher, calls Recovery. ISO
  • throw(Ball) Raises an exception Ball. ISO

Term unification

  • X = Y Unifies X with Y. ISO
  • unify_with_occurs_check(X, Y) Unifies X with Y with occurs check. ISO
  • X \= Y Succeeds iff X and Y are not unifiable. ISO
  • subsumes_term(General, Specific) Succeeds iff there's a substitution θ such that Generalθ = Specificθ and Specificθ = Specific. ISO

Type testing

  • var(X) Succeeds iff X is a variable. ISO
  • atom(X) Succeeds iff X is an atom. ISO
  • integer(X) Succeeds iff X is an integer. ISO
  • float(X) Succeeds iff X is a float. ISO
  • atomic(X) Succeeds iff X is neither a variable nor a compound. ISO
  • compound(X) Succeeds iff X is a compound. ISO
  • nonvar(X) Succeeds iff X is not a variable. ISO
  • number(X) Succeeds iff X is either an integer or a float. ISO
  • callable(X) Succeeds iff X is either an atom or a compound. ISO
  • ground(X) Succeeds iff X is a ground term. ISO
  • acyclic_term(X) Succeeds iff X is acyclic. ISO

Term comparison

  • X @=< Y Either X == Y or X @< Y. ISO
  • X == Y Equivalent to compare(=, X, Y). ISO
  • X \== Y Equivalent to \+compare(=, X, Y). ISO
  • X @< Y Equivalent to compare(<, X, Y). ISO
  • X @> Y Equivalent to compare(>, X, Y). ISO
  • X @>= Y Either X == Y or X @> Y. ISO
  • compare(Order, X, Y) Compares X and Y and unifies Order with either <, =, or >. ISO
  • sort(List, Sorted) Succeeds iff Sorted unifies with a sorted list of List. ISO
  • keysort(Pairs, Sorted) Succeeds iff Pairs is a list of Key-Value pairs and Sorted unifies with a permutation of Pairs sorted by Key. ISO

Term creation and decomposition

  • functor(Term, Name, Arity) Succeeds iff Term ia either a compound term of Name and Arity or an atom of Name and Arity = 0. ISO
  • arg(N, Term, Arg) Succeeds iff Arg is the N-th argument of Term. ISO
  • Term =.. List Succeeds iff List is a list of the functor and arguments of Term. ISO
  • copy_term(Term1, Term2) Creates a copy of Term1 and unifies it with Term2. ISO
  • term_variables(Term, Vars) Succeeds iff Vars is a list of variables appear in Term. ISO

Arithmetic evaluation

  • Result is Expression Evaluates Expression and unifies it with Result. ISO
    • Expression is either:

      • integer,

      • float, or

      • evaluable functors
        • X + Y
        • X - Y
        • X * Y
        • X // Y
        • X / Y
        • X rem Y
        • X mod Y
        • -X
        • abs(X)
        • sign(X)
        • float_integer_part(X)
        • float_fractional_part(X)
        • float(X)
        • floor(X)
        • truncate(X)
        • round(X)
        • ceiling(X)
        • +(X)
        • X div Y
        • X ** Y
        • sin(X)
        • cos(X)
        • atan(X)
        • exp(X)
        • log(X)
        • sqrt(X)
        • max(X, Y)
        • min(X, Y)
        • X ^ Y
        • asin(X)
        • acos(X)
        • atan2(X, Y)
        • tan(X)
        • pi
        • X >> Y
        • X << Y
        • X /\ Y
        • X \/ Y
        • \X
        • xor(X, Y)
  • succ(X, S) Succeeds iff S is the successor of the non-negative integer X. prologue

Arithmetic comparison

  • E1 =:= E2 Succeeds iff E1 and E2 are evaluated to EV1 and EV2 respectively and EV1 equals to EV2. ISO
  • E1 =\= E2 Succeeds iff E1 and E2 are evaluated to EV1 and EV2 respectively and EV1 does not equal to EV2. ISO
  • E1 < E2 Succeeds iff E1 and E2 are evaluated to EV1 and EV2 respectively and EV1 is greater than EV2. ISO
  • E1 =< E2 Succeeds iff E1 and E2 are evaluated to EV1 and EV2 respectively and EV1 is greater than or equal to EV2. ISO
  • E1 > E2 Succeeds iff E1 and E2 are evaluated to EV1 and EV2 respectively and EV1 is less than EV2. ISO
  • E1 >= E2 Succeeds iff E1 and E2 are evaluated to EV1 and EV2 respectively and EV1 is less than or equal to EV2. ISO

Clause retrieval and information

  • clause(Head, Body) Succeeds iff Head :- Body unifies with a clause in the DB. ISO
  • current_predicate(PI) Succeeds iff the predicate indicated by PI is in the DB. ISO

Clause creation and destruction

  • asserta(Clause) Prepends Clause to the DB. ISO
  • assertz(Clause) Appends Clause to the DB. ISO
  • retract(Clause) Removes a clause that unifies withClause from the DB. ISO
  • abolish(PI) Removes the predicate indicated by PI from the DB. ISO
  • retractall(Head) Removes all the clauses which head unifies with Head from the DB. ISO

All solutions

  • findall(Template, Goal, Instances) Succeeds iff Instances unifies with a list of Template for each solution of Goal. ISO
  • bagof(Template, Goal, Instances) Succeeds iff Instances unifies with a bag (multiset) of Template for each solution of Goal. ISO
  • setof(Template, Goal, Instances) Succeeds iff Instances unifies with a set of Template for each solution of Goal. ISO

Stream selection and control

  • current_input(Stream) Succeeds iff Stream unifies with the current input stream. ISO
  • current_output(Stream) Succeeds iff Stream unifies with the current output stream. ISO
  • set_input(S_or_a) Sets the current input stream to the stream indicated by S_or_a which is either the stream itself or its alias. ISO
  • set_output(S_or_a) Sets the current output stream to the stream indicated by S_or_a which is either the stream itself or its alias. ISO
  • open(File, Mode, Stream, Options) Opens the file File in Mode with Options and unifies the stream with Stream. ISO
    • Mode is either: read, write, or append.
    • Options is a list of stream options listed below:
      • type(T) Specifies the type of the stream. T is either text (default) or binary.
      • reposition(Bool) Specifies if the stream can be repositions. Bool is either true or false.
      • alias(A) Specifies the alias for the stream. A is an atom.
      • eof_action(Action) Specifies the action that will be taken when the input stream reached to the end. Action is either:
        • error which throws an exception,
        • eof_code which returns a value indicating the end of stream (default), or
        • reset which resets the stream.
  • open(File, Mode, Stream) Equivalent to open(File, Mode, Stream, []). ISO
  • close(S_or_a, Options) Closes the stream indicated by S_or_a which is the stream itself or its alias. ISO
    • Options is a list of:
      • force(Bool) Specifies if an exception will be raised when it failed to close the stream. Bool is either false (default) or true.
  • close(S_or_a) Equivalent to close(S_or_a, []). ISO
  • flush_output(S_or_a) Sends any buffered output to the stream indicated by S_or_a which is either the stream itself or its alias. ISO
  • flush_output Equivalent to current_output(S), flush_output(S). ISO
  • stream_property(Stream, Property) Succeeds iff the stream Stream has the property Property. ISO
    • Property is either:
      • file_name(F)
      • mode(M)
      • input
      • output
      • alias(A)
      • position(P)
      • end_of_stream(E)
      • eof_action(A)
      • reposition(Bool)
      • type(T)
  • at_end_of_stream Equivalent to current_input(S), at_end_of_stream(S). ISO
  • at_end_of_stream(S_or_a) Succeeds iff the stream indicated by S_or_a which is either a stream or an alias has the property either end_of_stream(at) or end_of_stream(past). ISO
  • set_stream_position(S_or_a, Position) Sets the position of the stream indicated by S_or_a which is either a stream or an alias to the position Position. ISO

Character input/output

  • get_char(S_or_a, Char) Succeeds iff Char unifies with the next character from the stream indicated by S_or_a which is either a stream or an alias. ISO
  • get_char(Char) Equivalent to current_input(S), get_char(S, Char). ISO
  • get_code(S_or_a, Code) Succeeds iff Char unifies with the next code from the stream indicated by S_or_a which is either a stream or an alias. ISO
  • get_code(Code) Equivalent to current_input(S), get_code(S, Code). ISO
  • peek_char(S_or_a, Char) Similar to get_char(S_or_a, Char) but doesn't consume the character. ISO
  • peek_char(Char) Equivalent to current_input(S), peek_char(S, Char). ISO
  • peek_code(S_or_a, Code) Similar to get_code(S_or_a, Code) but doesn't consume the code. ISO
  • peek_code(Code) Equivalent to current_input(S), peek_code(S, Code). ISO
  • put_char(S_or_a, Char) Outputs the character Char to the stream indicated by S_or_a which is either a stream or an alias. ISO
  • put_char(Char) Equivalent to current_output(S), put_char(S, Char). ISO
  • put_code(S_or_a, Code) Outputs the code Code to the stream indicated by S_or_a which is either a stream or an alias. ISO
  • put_code(Code) Equivalent to current_output(S), put_code(S, Code). ISO
  • nl(S_or_a) Outputs a newline to the stream indicated by S_or_a which is either a stream or an alias. ISO
  • nl Equivalent to current_output(S), nl(S). ISO

Byte input/output

  • get_byte(S_or_a, Byte) Succeeds iff Byte unifies with the next byte from the stream indicated by S_or_a which is a stream or an alias. ISO
  • get_byte(Byte) Equivalent to current_input(S), get_byte(S, Byte). ISO
  • peek_byte(S_or_a, Byte) Similar to get_byte(S_or_a, Byte) but doesn't consume the byte. ISO
  • peek_byte(Byte) Equivalent to current_input(S), peek_byte(S, Byte). ISO
  • put_byte(S_or_a, Byte) Outputs the byte Byte to the stream indicated by S_or_a which is either a stream or an alias. ISO
  • put_byte(Byte) Equivalent to current_output(S), put_byte(S, Byte). ISO

Term input/output

  • read_term(S_or_a, Term, Options) Succeeds iff Term unifies with the next term from the stream indicated by S_or_a which is a stream or an alias. ISO
    • Options is a list of read options listed below:
      • variables(Vars) the list of variables appeared in Term
      • variable_names(VN_list) the list of A = V where A is an atom which name is the string representation of V and V is a variable appeared in Term
      • singletons(VN_list) similar to variable_names(VN_list) but those of variables that appeared once.
  • read_term(Term, Options) Equivalent to current_input(S), read_term(S, Term, Options). ISO
  • read(S_or_a, Term) Equivalent to read_term(S_or_a, Term, []). ISO
  • read(Term) Equivalent to current_input(S), read(S, Term). ISO
  • write_term(S_or_a, Term, Options) Outputs Term to the stream indicated by S_or_a which is either a stream or an alias. ISO
    • Options is a list of write options listed below:
      • quoted(Bool) Bool is either true or false. If true, atoms and functors will be quoted as needed.
      • ignore_ops(Bool) Bool is either true or false. If true, operators will be written in functional notation.
      • variable_names(VN_list) VN_list is a proper list which element is a form of A = V where A is an atom and V is a variable. Each occurrence of V will be replaced by the leftmost and unquoted A.
      • numbervars(Bool) Bool is either true or false. If true, terms '$VAR'(0), '$VAR'(1), ... will be written as A, B, ...
  • write_term(Term, Options) Equivalent to current_output(S), write_term(S, Term, Options). ISO
  • write(S_or_a, Term) Equivalent to write_term(S_or_a, Term, [numbervars(true)]). ISO
  • write(Term) Equivalent to current_output(S), write(S, Term). ISO
  • writeq(S_or_a, Term) Equivalent to write_temr(S_or_a, Term, [quoted(true), numbervars(true)]). ISO
  • writeq(Term) Equivalent to current_output(S), writeq(S, Term). ISO
  • write_canonical(S_or_a, Term) Equivalent to write_term(S_or_a, Term, [quoted(true), ignore_ops(true)]). ISO
  • write_canonical(Term) Equivalent to current_output(S), write_canonical(S, Term). ISO
  • op(Priority, Specifier, Operator) Alters the operator table. ISO
  • current_op(Priority, Specifier, Operator) Succeeds iff the operator indicated by Priority, Specifier, Operator is in the operator table. ISO
  • char_conversion(In, Out) Alters the character conversion mapping. ISO
  • current_char_conversion(In, Out) Succeeds iff the character conversion from In to Out is in the conversion mapping. ISO

Logic and control

  • \+Goal Succeeds iff call(Goal) fails. ISO
  • once(Goal) Calls Goal but never redoes. ISO
  • repeat Repeats the following code until it succeeds. ISO
  • call(Closure, Arg1, ..., ArgN) N = 1..7. Succeeds iff call(Goal) where Goal is Closure with additional arguments Arg1, ..., ArgN. ISO
  • false Equivalent to fail. ISO
  • between(Lower, Upper, X) Succeeds iff Lower <= X <= Upper. prologue

Atomic term processing

  • atom_length(Atom, Length) Succeeds iff Length is the number of runes in Atom. ISO
  • atom_concat(Atom1, Atom2, Atom3) Succeeds iff Atom3 is a concatenation of Atom1 and Atom2. ISO
  • sub_atom(Atom, Before, Length, After, SubAtom) Succeeds iff SubAtom is a sub atom of Atom where Before is the number of runes before SubAtom, Length is the length of SubAtom, and After is the number of runes after SubAtom. ISO
  • atom_chars(Atom, List) Succeeds iff List is the list of single-rune atoms that Atom consists of. ISO
  • atom_codes(Atom, List) Succeeds iff List is the list of runes that Atom consists of. ISO
  • char_code(Char, Code) Succeeds iff Char is a single-rune atom which rune is Code. ISO
  • number_chars(Number, List) Succeeds iff List is the list of single-rune atoms that represents Number. ISO
  • number_codes(Number, List) Succeeds iff List is the list of runes that represents Number. ISO

Implementation defined hooks

  • set_prolog_flag(Flag, Value) Sets the Prolog flag Flag to Value. ISO
    • Flag is either:
      • char_conversion Value is either on or off (default).
      • debug Value is either on or off (default).
      • unknown Value is either error (default), fail, or warning.
      • double_quotes Value is either chars (default), codes, or atom.
  • current_prolog_flag(Flag, Value) Succeeds iff Value is the current value for the Prolog flag Flag. ISO
    • Flag is either:
      • bounded Value is always true.
      • max_integer Value is always 9223372036854775807.
      • min_integer Value is always -9223372036854775808.
      • integer_rounding_function Value is always toward_zero.
      • char_conversion Value is either on or off (default).
      • debug Value is either on or off (default).
      • max_arity Value is always unbounded.
      • unknown Value is either error (default), fail, or warning.
      • double_quotes Value is either chars (default), codes, or atom.
  • halt(X) Exits the host program with the status code of X. ISO
  • halt Equivalent to halt(0). ISO

Definite clause grammars

  • expand_term(In, Out) Succeeds iff Out is an expansion of the term In.
  • phrase(Phrase, List, Remainder) Succeeds iff the different list List-Remainder satisfies the grammar rule Phrase.
  • phrase(Phrase, List) Equivalent to phrase(Phrase, List, []).

List processing

  • member(X, L) Succeeds iff X is a member of the list L. prologue
  • append(Xs, Ys, Zs) Succeeds iff Zs is the concatenation of Xs and Ys. prologue
  • length(List, Length) Succeeds iff Length is the length of List. prologue
  • select(X, Xs, Ys) Succeeds iff X is an element of Xs and Ys is Xs with one occurence of X removed. prologue
  • maplist(Goal, List1, ..., Listn) n = 1..7. Succeeds iff List1, ..., Listn are the list of the same length and call(Goal, List1_i, ..., Listn_i) succeeds for all the i-th elements of List1, ..., Listn. prologue
  • nth0(N, List, Elem) Succeeds iff Elem is the N-th element of List counting from 0.
  • nth1(N, List, Elem) Succeeds iff Elem is the N-th element of List counting from 1.

Program

  • consult(File) Loads Prolog program files indicated by File. File is either an atom or a list of atoms. An atom abc indicates a Prolog program file ./abc or ./abc.pl.
  • [File|Files] Equivalent to consult([File|Files]).
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