Custom Functions

Sometimes the functions supplied by CT and addons just won’t do it. Here’s how to write your own functions! You can even nest functions in functions

Basic Syntax

Generally, you declare a function using:

function NAME ([arguments[as type]]) [as returnType]{
    [return VALUE;]

The things in brackets are optional, depending on what you want to achieve. Let’s take a closer look at specific functions.

Void functions

Void functions are functions that will not return any value.

//calls the function tens() without arguments

//calls the function realTens() with the String "Hello World!" as argument
realTens("Hello World!");

//crates function tens() with no required arguments
function tens(){
    //Calls function realTens() with "" as argument

//creates function realTens() with one string required as argument
function realTens(a as string){
    //prints the argument 10 times
    for i in 1 to 11{

Return functions

You can also specify a value that should be returned by a function. It is recommended using the as keyword to define the return type.

//calls add function with 1 and 99 as parameters
val result = add(1,99);

//you can place the add function inside the print function as well

//defines function add() with a and b as parameters (both set to be Integers!) and sets the return type to Integer
function add(a as int,b as int) as int{
    //returns the sum of a and b
    return a+b;

Recipe functions

CT’s shaped and shapeless recipes natively support functions to alter the recipe’s outputs After declaring a recipe’s output and inputs, you can add a function as third parameter, that will require 3 parameters: (output, inputs, craftingInfo)

To show this, we’re gonna create a recipe that repairs your precious diamond Pickaxe using diamonds:

val diaPick = <minecraft:diamond_pickaxe>;

//we start normal, by writing the output

//followed by the input array. One change though - we mark the diamond pickaxe, so we can use it in the function later

//now we start declaring the function. 
//It needs 3 parameters, one for the output, one for the inputs and one for crafting info. 
//We'll only need the input parameter, though.
function(out, ins, cInfo){

    //now we return the pickaxe with either 0 DMG or Current damage -10, whatever is higher. This is to prevent negative damage values.
    return ins.mark.withDamage(max(0,ins.mark.damage - 10));