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Paradigm(s) Logic programming
Designed by Mauro Gazzelloni
Developer Mauro Gazzelloni
Appeared in January 2000
Stable release 1.04 / April 2013
Influenced by Prolog, C
Implementation language C++
OS Microsoft Windows
License 2000-2014 Mauro Gazzelloni
Website Project Site

CLACL, representing CLAC-Language (where CLAC stands for Logical Composition with the Assistance of Computers) is the result of ongoing theoretical research which aims to provide a formal description of the logical choices relating to the definition of organisational processes of composition.

The logic of CLACL is not based on the processing of numerical information, but it is on 'spatial-relational' information. They generate a logical configuration. Then, with a tool called Plasma you can shape the created domain in a physical form such as music or graphics.

An example of Instances and Domain

An example of a Model

CLACL is an interpreted language and integrated into a production environment that provides several tools to facilitate the writing of the code and its graphical representation.

The first version (00.02.00) of the language was made available on the Internet in 2000 at the site of the project. The version 00.06.00 was distributed at the 2009 Festival of Mathematics held in Rome, during which the project CLAC was presented.

Characteristics of the Language[edit]

The target of potential users of the language are those whom work within the creative fields in different areas: from design to music.

Example of creative generation created with CLACL.

Every design work produces an organism, more or less complex and complete, in which all of its parts are in mutual relation. To ease the description let us consider the graphic planning, that is the design and realization of a graphic pattern. Those that have had a chance to prepare a composition, know that every element should be in a precise relation with the others and only when all the elements are balanced can the composition be considered done. This is a process that can be proven and verified.

Since the compositional process is guided by logical choices, the program is centred around the information science area of Artificial Intelligence. It is for this reason that the project is mentioned in the entry Computational creativity External_links in the Wikipedia as one of the few examples of the application of Information science to creativity.

The closely logic-driven syntax, somewhat challenging for anyone not accustomed to working in AI, was supplemented by constructs more readily usable in practice.

As an example, see the description of a cycle (loop) implemented in Prolog and CLACL.

With the following example in prolog, a loop is run that prints the loop index:

loop(X,Y) :-
    !,X < Y,
    X2 is X + 1,

In CLACL, a the similar process, is carried out using the following code:

 @PRINT("$x $y",NL)
 FOR ( $x, $y ) IN II[]


$x $y
!a !a
!a !b
!a !c
!b !a
!b !b
!b !c
!c !a
!c !b
!c !c

the formalism of the cycle in CLACL is carried out in a very similar way to the C-Language. ≈The language adopts a combination of the declarative and procedural paradigms. The two languages are Prolog and C-Language. The declarative aspect comes from prolog and is used in statements and in scanning the tree of alternatives (backtracking). The procedural aspect is derived from C-Language and is highlighted in particular in the control structures of the procedural flow.

Structure of the language[edit]

The commands are listed in a script that is subjected to an interpreter that generates the result. The purpose of the carrying out of controls is to produce a logical configuration of entities and represent it in graphic form, and as such, as a product of processing, there will be a graph. The set of entities that form part of the graph is called a domain.

CLACL has three groups of statements:

  • Declarations
  • Controls
  • Commands

The declarations reflect the situations of the domain and are the most similar to Prolog.
The controls implement constructs for controlling the flow of the code with loops and expressions.
The commands require or set conditions on the domain.

As with all programming languages, CLACL implements the following key concepts:

  • Variable
  • Instruction
  • Expression
  • Control structures
  • Subprogram
  • Information structures

and additionally implements specialist concepts of the domain of the issues which address:

  • Statements
  • Tests
  • States

The entities that can be generated via the interpretation of the script are:

  • instances
  • relations
  • models
  • shapes
  • figure
An instance can be seen as a geometric point in the plane but we are not interested in its position; our interest is its existence within the domain and its relationship with other entities.
A relation describes the relationship between different instances.
A model allows the description of complex relations.
The shape describes the characteristics of a logical figure.
A logical figure can be seen as a geometrical figure.
Application of figures realized with CLACL


Generation of an instance:




Generation of a relation:

relation:rl1(instance:a, instance:b)


&rl1(!a, !b)

Definition of a model that represents a triangular configuration:

define model: tris(!a,!b,!c)

Implementation of a cycle:

FOR ($a$,b) in SET[]
    @PRINT(“Instances “,$a,“ - “,$b,NL)

Implementation of a condition

CASE ($x == 0)
    @PRINT(“The value of $x is zero“,NL)

Definition of a function:

define function: switch($a$,b$,c)
    CASE ($a == 1)
        @PRINT($b,” - “,$c,NL)
    CASE ($a == 2)
        @PRINT($c,” - “,$b,NL)

some operations on the set:

def INSI1[4]  // definition of the set of 4 items
ST1[] = [ ST1[] + ST2[] ]    // add
ST1[] = [ ST1[] - ST2[] ]    // subtract
( ST1[] == ST2[] )    // equals

Example of a logic expression:

(( ST1[] == ST2[] ) AND (( ST3[] == ST2[] ) OR ( ST4[] == ST1[] )) AND pos(!a == !b))

Hypothesis about the project by Michelangelo[edit]

The design of the Piazza del Campidoglio by Michelangelo has not survived. The project is based on drawings made at second hand. With CLACL was made a compositional hypothesis on a new basis.

Composition of the Piazza del Campidoglio with CLACL.

Spatial Expression Example[edit]


  1. f=shape:frmSquare4(!a,!b,!c,!d)


FOR ($x) IN I[]
  CASE(pos(!$x IN #f))

Using spatial expression with CLACL

CLAC Tutorials[edit]

Books about CLAC[edit]

See also[edit]


External links[edit]