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interpret

Basic interpreter for EVAL language. (totally invented :))

USAGE

interpret < file

EVAL language

The language is executed line per line.

Loop

while(E) E end

Test

if(E) E end

Variable declaration + affectation

V = E

Function call

foo(E)

Comments

Starting by # eg: a = a+b # A comment

Grammar

E = expression F = function R = float o = operator V = variable

E --> if(E) E --> while(E) E --> end E --> (E) E --> F(E) E --> V=E E --> R E --> V E --> EoE

o --> [+ - / ^ * % > < <= >= == !=]{1} V --> [A-Za-z]+ F --> [A-Za-z]+ R --> [-+]{0,1}[0-9.]+

Operators

• a = b -> true if a is egual b
• a > b -> true if a greater than b
• a < b -> true if a lower than b
• a ~ b -> true if a not egual to b
• a + b -> a add b
• a - b -> a sub b
• a * b -> a mul b
• a % b -> a mod b
• a / b -> a div b
• a ^ b -> a power b

Operators priority

• =, >, >, <, ~ ===> 1
• +,- ===> 2
• *,/,% ===> 3
• ^ ===> 4

You can use the () for change the priority.

Predefined functions

print(E) ===> print the value of the expression abs(E) ===> calc the absolute value of the expression sqrt(E) ===> function sqrt cos(E) ===> function cos

EXAMPLES

You can read test.txt, it's a basic program written in EVAL. It print all prime numbers between 1 and 1000.

TODO

• The ELSE structure : if(E) E else E end
• Functions definitions : def:f(x) E end
• Multi-parameters functions
• Better errors management
• Multi-chars operators
• Multi-types (dynamic) : double, int, string, list
• Very big numbers.