xlang

Very simplistic programming language implemented in Java

Language specification

• Can only handle numbers
• In conditional statements 0 represents false and all others values are considered true
• Shift down indentation level by skipping trailing ;
• The only operators are +, -, * and /
• Variable names must start with a letter but can contain numbers

Syntax

On Backus-Naur Form:

<stmt-sequence> ::= <stmt>  { ; <stmt>}
<stmt> ::= <assign-stmt> | <output-stmt> | <if-stmt> | <while-stmt>
<assign-stmt> ::= <var> = <expr>
<output-stmt> ::= output <expr>
<if-stmt> ::= if <expr> then <stmt-sequence> else <stmt-sequence> endif
<while-stmt> ::= while <expr> do <stmt-sequence> done
<expr> ::= <term> {<add-operator> <term>}
<term> ::= <factor> {<mult-operator> <factor>}
<factor> ::= (<expr>) | <cardinal> | <var>
<add-operator> ::= + | ?
<mult-operator> ::= * | /
<cardinal> ::= <digit> {<digit>}
<digit> ::= 0 | 1 | 2 | .... | 9
<var> ::= <letter> {<letter> | <digit>}<letter> ::= a | b | ... | z | A | B | ... | Z

Examples

Example of a program calculating the fibonacci sequence:

a = 1;
b = 0;
i = 0;

while (5-i) do
    a = b+a;
    b = a+b;
    output a;
    output b;
    i = i+1
done;