Chapter 4.1: Functions

If you want your program to stay organized and readable, it’s best to group related code into functions.

Functions are reusable blocks of code that can be executed at any time in your program. They can take in values (called arguments) and can optionally return a result (a returned value).

func my_function(argument) {
    bark(argument);
}

my_function("Hello, world!");

Function Definitions

Creating your own function is simpler than it looks.

You start with the func keyword, give it a name (just like a variable), then specify any arguments it should take, followed by the code to run.

func the_name_of_a_function(argument1, argument2) {
    # ...
}

Arguments are objects that the function receives when it’s called. These can then be used within the function’s code.

func define_x(value) {
    obj x = value;
}

If you want your function to send something back when it’s done, use the give keyword to return a value.

func return_value(value) {
    give value;
}

bark(return_value("Hello, world!"));  # outputs 'Hello, world!'

Function Calls

Once a function is defined, it won’t run until you call it. To call a function, use its name followed by parentheses () and include arguments if the function expects them.

If it doesn’t take any arguments, just call it with empty parentheses.

func my_function(x) {
    give(x + 1);
}

obj ten_plus_one = my_function(10);

When calling functions, arguments are positional. That means if a function expects 2 arguments, you must pass exactly 2, not more, not less.

func no_args() {
    give;
}

no_args("Secret argument"); # this line will cause an error