Functions

Functions are reusable procedures (custom blocks) that can return values, including primitives or structs. Functions always run in Run without screen refresh mode and must only be called from other Run without screen refresh procedures or functions to prevent undefined behavior.

Each function must end with a return statement. Using stop_this_script inside a function is undefined behavior.

Declaring a Function

Use the func keyword to define a function. Optionally, include a return type for functions that return a struct.

func my_function(x, y) {
    return $x + $y;
}

func my_function(x, y) MyStruct {
    return MyStruct { ... };
}

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Returning Struct Variables

Functions can return struct variables by specifying the struct type as the return type.

Basic Struct Return Example

struct Vector {
    x,
    y
}

func vec_add(Vector lhs, Vector rhs) Vector {
    return Vector {
        x: $lhs.x + $rhs.x,
        y: $lhs.y + $rhs.y
    };
}

Using the Returned Struct

# Create vectors
Vector vec1 = Vector { x: 10, y: 20 };
Vector vec2 = Vector { x: 5, y: 15 };

# Call function that returns a struct
Vector result = vec_add(vec1, vec2);

# Access the returned struct's fields
say result.x; # Outputs: 15
say result.y; # Outputs: 35

Note

When returning struct variables from functions, the return type must be explicitly specified when returning a struct

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Default Argument Values

Function parameters can have default values, allowing callers to omit them:

func greet(name = "world") {
    return "Hello, " & $name & "!";
}

• greet() returns "Hello, world!"
• greet("aspizu") returns "Hello, aspizu!"

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Calling a Function

Functions are called by name with argument values:

say my_function(1, 2);

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Keyword Arguments

You can also call functions using keyword arguments, which specify parameter names explicitly. This is useful when using default arguments or calling functions with many parameters:

greet(name: "aspizu")

This behaves the same as greet("aspizu"), but makes the call more readable—especially when multiple parameters are involved:

func introduce(name, title = "developer", location = "unknown") {
    return $name & " is a " & $title & " from " & $location;
}

Call it with keyword arguments:

introduce(name: "aspizu", location: "India")
# Equivalent to: introduce("aspizu", "developer", "India")

Note

Keyword arguments can be used in any order, as long as the required parameters are provided:

introduce(location: "Berlin", name: "Kai");
# Still valid