melkior: A C# repository from eugenioenko

Melkior interpreter

This is a work in progress of an interpreter writen in c# of a scripting language somewhat related to lua/python family. This project also includes a transpiler of melkior language into javavscript.

variable definition

// numbers
var number_1 = 0.00001;
var number_2 = 9999999;

// string
var string_1 = "string";

// boolean
var boolean_1  = true;
var boolean_2 = false;

// array
var array_1 = [1, 2, 3, 4, 5];
var array_nested = ["one", "two", "three", ["nested_1", "nested_2", array_1]];
print array_nested[3];

// dictionary
var dict_1 = {
    entry_1: "first entry",
    entry_2: "second entry"
};

control statements

if number_1 == number_2 then
    print "number_1 equals number_2";
else
    print "numbe_1 is not equal number_2";
end

// mutliple "else if": elseif

if number_1 == number_2 then
    print "number_1 equals number_2";
elseif number_1 == 0.00001 then
    print "number_1 equals 0.0001";
else
    print "number_1 is not 0.0001 nor number_2";
end

// logical operators: and, or , not

if number_1 >= 0 and number_1 < 100 then
    print "number_1 is between 0 and 100";
end

ternary operator

condition
    yep "true expression"
    nop "false expression";

var variable_2 = variable_1 == true
    yep "variable_2 equals variable_1"
    nop "variable_2 does not equal variable_1";

block statement

Inside each new block a closure is generated

var alpha = "global";
var beta = "global"";
do
    var beta = "local";
    print alpha; // global
    print beta;  // local
end

Loop statements

while

while condition do
    // statements
end

repeat while (do while)

repeat
    // statement;
    // statement;
while condition

foreach

foreach item in array_1 do
    print item;
end

foreach with index/key

foreach item with index in array_1 do
    print index + ': ' + item;
end

functions

In melkior the body of the function is a block statement which must finish with "end"

func function_1(alpha, beta)
    var result = alpha + beta;
    return result;
end

Anonymous functions

When passing a function as argument to another function its possible to use a nameless function

["green", "blue", "red"].each(
    func(value, index, array) do
        print index + ": " + value;
    end
);

Lambda functions

Lambda functions are anonymous functions with a single shorthand return statement in their body

var square = [0, 1, 2, 3].map(
    lambda(num) => num * num
);

The previous snippet is equivalent to

var square = [0, 1, 2, 3].map(
    function(num) do
        return num * num
    end
);

semicolons

Semicolons are required after each

expression statements
var statement
print statement

classes

Classes are defined by using the reserved keyword "class" folowed by a class name. To inherit a class from another use "inherits" keyword after class name definition. Class body consist of function definitions; To create a new instance use "new" keyword folowed by the Class name and arugment list to call the constructor function.

class ParentClass
    
    constructor(alpha) 
        this.alpha = alpha;
    end

    method()
        print this.apha;
    end

end

class ChildClass inherits ParentClass
    
    constructor(alpha, beta)
        base.constructor(alpha); 
        this.beta = beta;
    end

    method()
        base.method();
        print this.beta;
    end

    static(alpha, beta)
        return alpha + beta;
    end

end

var parentInstance = new ParentClass("alpha");
var childInstance = new ChildClass("beta", "gama");
print ChildClass.static("one", "two");

running the interpreter

Execute Melkior from the console passing the source code filename as argument. Melkior accepts any file extension, currently there is a small demo in the root folder of the project DemoCode.mel

Melkior.exe source_code.mel
Melkior.exe source_code.mel

passing arguments from command line

It is possible to pass arugments from command line, just append them after the source code filename. If a main function is defined in the source code, Melkior will execute the funcion and pass the command line argumetns as arguments

Melkior.exe source.mel argument_1 argument_2 argument_3

And in the source code

func main(args)
    args[0] == "argument_1";
    args[1] == "argument_2";
end

transpiling to Javascript

It is possible to transpile melkior source code into javascript. It can be done through the cli with --t argument.

Melkior.exe source.mel --t

Melkior will create a new sourcefile with javascript syntaxis by apending .js to the orignal filename

eugenioenko/melkior