Type System

The types

Bosscript has the following types built into the language:

  1. broj - numbers
  2. tekst - strings
  3. logicki/logički - booleans
  4. objekat - objects
  5. niz - arrays
  6. bajt - byte
  7. BajtNiz - ByteArray
  8. funkcija - functions
  9. nedefinisano - null and undefined
  10. ReadonlyObject - an extension of objekat used only internally

Broj

The broj type represents all numbers, both integers and floating-point numbers. It is the equivalent of the number type in JavaScript. The maximum value a broj holds is 3.4028235 * 1038. Under the hood, it uses the double type from the JVM. Below are some examples:

var x = 10;
var y = 1.234;
var z = 0;

broj also supports adding underscores as separators, for readability purposes:

var x = 1_000_000 // valid, holds 1000000 (one million)
var z = 1_00_00_00 // bad readability, but still valid, holds 1000000 (one million)

The separators can be placed however the user likes - the Bosscript lexer just ignores them when handling numeric literals. However, we do recommend using them consistently and in a way that is readable.

All commonly used operators are supported by broj, including +, -, *, /, and %. There is also the ^ operator, which is used for exponentiation:

ispis(5^3); // prints 125

Tekst

The tekst type represents strings. It is a direct equivalent of the String type from the JVM. The only difference between Bosscript’s tekst and most other string representations in other programming languages is the delimiter. The only valid delimiter for tekst are double quotes. Single quotes are not allowed:

var name = "Bosscript";
var version = '1.0';

Other than that, tekst behaves exactly the same as other string implementations. It comes with various utility methods built in. Read more about them in the tekst api page

Logički

The logički / logicki type represents booleans. Both spellings are supported and treated equally by the interpreter, as is the case for all keywords with bosnian-specific letters. It is built on top of JVM Boolean and behaves exactly the same. The only difference is the literals themselves, which are Bosnian words:

var t1 = tačno;
var t2 = tacno;

var nt1 = netačno;
var nt2 = netacno;

As you can see, even the literals support spelling with or without the letter č. All four variable declarations are valid.

The type has no built-in methods itself.

Objekat

The objekat type is very similar to JavaScript objects. It is a collection of related data, which is stored as key-value pairs. Under the hood, it is implemented as a HashMap. The keys of an objekat are identifiers, while the value can be of any type supported by Bosscript. Consider the following example:

var empty = {};

var obj = {
    a: "a",
    b: 1,
    c: tacno,
    d: [1, 2],
    e: {
        isNested: tacno,
        prop: "prop"
    },
    f: funkcija(){
        ispis("fn");
    }
}

The obj object holds data of various types. To access any of the properties, use the dot syntax:

ispis(obj.b); // prints 1

Trying to access a property that doesn’t exist will result in an error:

obj.rand;

Property 'rand' does not exist on object {a: "a", b: 1, ...}

Properties can also be accessed with the bracket indexing operator, where the property is referenced as a string literal:

obj["c"] // evaluates to tačno

Trying to access a property that doesn’t exist with the bracket operator also results in an error:

obj["rand"]

However, it is possible to assign to properties that don’t already exist:

obj.notDefinedYet = "NOW DEFINED";
obj["notDefined"] = "NOW DEFINED TOO";

Both expressions above are valid and will create new properties on the obj object.

An object property can also be a function. We see that obj.f is a function expression. Here is how to use it:

obj.f();
// prints 'fn' to the console

When defining an object function, you can reference other object properties within the function, via @:

var o = {
    name: "Bosscript",
    greet: funkcija(){
        ispis("Hello, my name is " + @name);
    }   
}

o.greet();

// Prints 'Hello, my name is Bosscript' to the console

The @ symbol is a reference to the object itself. It is the equivalent of the this keyword in most programming languages. Using @, you can access any object property within object functions. You cannot use @ outside of object methods. Consider this example:

var o = {
    x: 1,
    y: 5,
    z: @x + @y 
}

Code like the example above will cause an error @ does not exist.. So, only use @ in functions.

Note: @ is also used in models. Read more here.

Niz

The niz type represents arrays. It behaves similarly to JavaScript’s array or Kotlin’s ArrayList, which it uses under the hood. In Bosscript, an array is dynamic, meaning it can hold data of different data types at once. An array literal is written as a comma separated list of values between brackets. Consider the following example:

var empty = [];
var a = [1, 2, 3, 4, 5];
var b = [1, "2", 3, "4", tačno];
var c = [1, [2, [3, 4]], 5];

All four declarations above are valid, and they demonstrate the flexibility of niz.

A niz is indexable using the bracket indexing operator, just like arrays in most programming languages:

var arr = ["A", "B", "C"];
ispis(arr[0]);

// prints 'A'

Indexes are 0-based, like in most other programming languages.

There are two ways to loop over a niz, either manually, or with the zaSvaki property, which is built into niz:

var arr = ["A", "B", "C"];
za svako (i od 0 do arr.zadnji()){
    ispis(arr[i]);
}

// prints A B C to the console

var arr = ["A", "B", "C"];
arr.zaSvaki(ispis);

// also prints A B C to the console

niz has many more built in properties like zaSvaki, which you can read more about here.

Bajt and BajtNiz

A bajt represents a byte, while BajtNiz is just an array of bytes. Bosscript v1.0 doesn’t support any byte literals. Instead, bajt is only used within BajtNiz, which itself is only used for input and output stream objects. You will only encounter BajtNiz when working with the telnet standard library package.

BajtNiz has built in functionality, which you can read more about here.

Funkcija

A funkcija represents a function. Just like in JavaScript and some other languages, a function can be passed around as an argument. Refering back to the zaSvaki example from before,

var arr = ["A", "B", "C"];
arr.zaSvaki(ispis);

// also prints 'A B C' to the console

we can see that ispis is being passed as an argument to the zaSvaki function. It is also possible to build anonymous lambda functions in-place in situations like this:

var arr = ["A", "B", "C"];
arr.zaSvaki(funkcija(str){
    ispis(str.malimSlovima());
});

// prints 'a b c' to the console

To learn more about functions, refer to the functions article. It goes into depth on how functions work in Bosscript. This section was just an overview of functions as a type.

Nedefinisano

The nedefinisano type is a special type which represents null and undefined. More precisely, Bosscript doesn’t distinguish between null and undefined in the way that Javascript does. Nedefinisano covers both. The word nedefinisano itself is a translation of undefined, and it was chosen because the Bosnian language doesn’t have an appropriate word for null.

nedefinisano can be used to initialize variables, but there is no need, since not providing any initial value does exactly that:

var nd = nedefinisano;
var x;

ispis(nd);
ispis(x);

// prints nedefinisano twice

It doesn’t have any built-in functionality and attempting to access a property of a nedefinisano variable will result in an error:

var str = getValueOrNull()
ispis(str);
// prints nedefinisano

str.malimSlovima();
// ^---------------------- Cannot read property malimSlovima of nedefinisano

ReadonlyObject

The ReadonlyObject is a type that is only used internally. It is an extension of the objekat type, with the only difference being the fact that its properties cannot be changed. Since many of the standard library packages provide objects, a special type was built to make sure the user doesn’t reassign any of their properties accidentally. Below is an example:

var klijent = TelnetKlijent();
klijent.ulazniTok = netačno;

Error: ulazniTok is readonly!

Other than that, you will not notice any difference when working with ReadonlyObject, when compared to regular objekat. Even printing its typename will yield “objekat”.

Typing

You will not need to think a lot about types when working with small Bosscript programs. Variables are fully dynamic. You will need to consider types in the context of functions, type definitions (which are used for quick user-defined types), and models. Find out more in the respective articles.