Fundamental research

Szablon:W edycji Work on programming language Loglan'82 and its compiler was accompanied by vivid discussion and fundamental research. On these pages we shall report some of results as well as an attempt to define an axiomatic semantics of Loglan'82.

Problems and reports

Safe dealocation of objects

We are happy to present you the object managing system invented by Antoni Kreczmar. In his system one can use the instruction kill(x) in order to dealocate an object being the value of the variable x.

The axiom of kill reads

[math](x=y=z \neq none) \implies \{kill(y)\}(x=y=z=none)[/math]

For more information see safe delocation of objects

How to determine the inherited class

One program may contain many classes of the same name. This is due to the block structure of Loglan programs.

Now, suppose that a class B inherits 9I.e. extends) class A. Which of possibly many classes A we should identify as a base class?

This question is a fundamental one for the definition of semantics. There are 4 languages which admit both nesting of modules (i.e. block structure ) and inheritance:

• Simula67
• Loglan'82
• BETA
• Java

Each language gives another definition of the base class. We shall mention ...

Part II Axiomatic definitions of sublanguages of Loglan'82

Here we shall present a increasing sequence of sublanguages Li of Loglan'82. For each language we shall present its grammar and a semantics as defined by some axioms and inference rules.

Program

Program in Loglan'82 has the following structure

program <name>;

<declarations>

begin

<instructions>

end

Declarations of variables. Assignment instructions

Example

program P2 ;

var x,y: integer;

begin

y:=74;

x:= y+ 8;

end

Grammar
Context free grammar

Well formed expressions

Axiom

[math]{x:=\tau}( \alpha ) \Leftrightarrow \alpha(x/\tau)[/math]