What's lang

Lang is dynamically typed interpreted programming language. The lang project is written just for fun, author is not going to take over the world.

Examples

Simple programs

More complex programs:

• Hash table;
• 99 bottles of beer;
• Fibonacci numbers computation;
• ...and some more tests.

Description

Types

• Primitive
  • Boolean
  • Integer
  • String
  • Undefined
• Arrays
• Structures
• Functions

Boolean

Just boolean with only two instances: true &false.

Operators: &&, ||, !.

Can be obtained from any value by using toBoolean method.

Conversion contracts:

• toBoolean same instance;
• toInteger 1 if true, 0 otherwise;
• toString "true" or "false".

Integer

32-bit integer. NaN supported. Decimal constants.

Can be obtained from any value by using toInteger method. If conversion not supported, NaN will be returned.

Operators: +, -, *, /, %, >>, <<, |, &, ^, ~.

Conversion contract:

• toBoolean false when 0 or NaN, true otherwise;
• toInteger same instance;
• toString String representing this integer in decimal system.

String

Literals (may be multiline) in double (") or single (') quotes.

Can be obtained from any value by using toString method.

Operators: +.

Methods:

• subString(fromInclusive, toExclusive)

Undefined type

Type with only one instance, named undefined. Conversion contract:

• toBoolean == false;
• toInteger == NaN;
• toString == "undefined".

Array

Container stored contiguously in memory. Can store elements of any other type at the same time.

New instance creation:

[] // empty array
[1, 2, 3] //array which contains 1, 2 and 3
[1, [2, true, ["s"]]] //array which contains 1 and array of 2, true and array of "s"   

Element access:

var array = [1, 2, 3];
array[1]; //2
array[1] = 0; //[1, 0, 3];
array[4[ = true; //[1, 0, 3, undefined, true] - autoexpansion

Methods:

• size() returns size of given array

array->size(); //5

Auto expansion:

Structures

Container with named-fields. Like C-struct or POJO.

Definition:

struct Point { //name
    x, y //fields
}

Instance creation:

var point = new Point(10, 20);

Fields access:

point->x + point->y; //30

Functions

Function is first-class object.

Definition(named):

function compute(x, y, z) { //name and arguments
    x + y + z; //return can be ommitted at the end of function
}

Definition(anonymous):

var lambda = \(x, y) x + y; // \(arguments) expression

Partial applying (arguments binding):

var computeX5 = compute(5);

Bound method:

var x = 123;
var toStrX = x->toString; // Important! No "()"! 

Call:

compute(1, 2, 3);  //6
computeX5(true, 'qwerty'); //compute(5, true, "qwerty") => (5 + 1) + "qwerty" => "6qwerty";
lambda(10, 20); // 30
x = 456;
toStrX() //"123" Important! Bound to object, contained in variable x, not to x! 
x->toString() //"456"