<s5>Æliens</s5> -- slide(s)

DLP -- introduces logic into object orientation

DLP = LP + OO + $||$

Design principles -- support for knowledge-intensive applications

objects -- dynamic states
processes -- communication by rendezvous
distributed backtracking -- exhaustive search

Objects -- a labeled set of clauses

DLP


  object name {
  var variables.
  
  constructor clauses
  method clauses
  }

slide: DLP -- terminology

Expressions -- terms

Prolog

constants -- a, "a string", $[ ]$
variables -- $X,Y,Z$
compound -- $f(a,X)$ , $[ H | T ]$

Unification -- bi-directional parameter passing

$f(X,a) = f(b,Y)$ results in $X = b$ and $Y = a$

slide: DLP -- expressions

Prolog


  p(X,Y) :- r(Z), b(X). // clauses
  p(X,Y) :- q(Y), b(X).
  b(X) :- a(X).
  b(0).  // facts
  a(1).
  q(2).

Query


  ?- p(X,Y). // results in (X = 1,Y = 2)
              // and (X = 0, Y = 2)

slide: DLP -- control (1)

List processing -- backtracking


  member(X,[X|_]).
  member(X,[_|T]) :- member(X,T).
  
  append([],L,L).
  append([ H | T ],L,[ H | R ]):- append(T,L,R).

slide: DLP -- control (2)

Additional statements

DLP

$v := t$ -- to assign to non-logical variables
$O = new(c(t))$ -- to create an active instance of the object c
$O!m(t)$ -- to call the method $m(t)$ for the object O
$accept(m1,...,m_n)$ -- to accept method requests

slide: DLP -- objects (1)

Computation model -- distributed logic

objects -- state + methods
processes -- to evaluate goals
communication -- backtrackable rendezvous

slide: DLP -- objects (2)

Object


  object travel {    travel  
  var cities = [amsterdam, paris, london].
  
  travel() :- accept( all ), travel().
  
  reachable(X) :- member(X, cities).
  add(X) :-
  	append( cities, [X], R), cities := R.
  }

Usage


   ?- O = new travel(), O!reachable(X), write(X).

slide: DLP -- objects (3)

Inheritance


  object agency : travel {    agency  
  agency() :- accept( any ), agency().
  book(X,Y) :-
  	reachable(X),
  	price(X,Y).
  price(amsterdam,5).
   ...
  }

slide: DLP -- inheritance

Techniques -- logic

meta programming
active intelligent agents

slide: DLP -- technology

The language DLP

design principles -- logic
terminology -- distributed backtracking
syntax -- Prolog + additional statements
objects -- non-logical instance variables
inheritance -- static
techniques -- active intelligent agents

slide: DLP -- summary

Æliens

2009

DLP -- introduces logic into object orientation

Design principles -- support for knowledge-intensive applications

Objects -- a labeled set of clauses

Expressions -- terms

Unification -- bi-directional parameter passing

Prolog

List processing -- backtracking

Additional statements

Computation model -- distributed logic

Object

travel

Usage

Inheritance

agency

Techniques -- logic

The language DLP