# Functions Functions in Slint are declared using the `function` keyword. Each function can have parameters which are declared within parentheses, following the format `name : type`. These parameters can be referenced by their names within the function body. Functions can also return a value. The return type is specified after `->` in the function signature. The `return` keyword is used within the function body to return an expression of the declared type. If a function does not explicitly return a value, the value of the last statement is returned by default. Functions can be annotated with the `pure` keyword. This indicates that the function does not cause any side effects. More details can be found in the [Purity](../concepts/purity.md) chapter. By default, functions are private and cannot be accessed from external components. However, their accessibility can be modified using the `public` or `protected` keywords. - A function annotated with `public` can be accessed by any component. - A function annotated with `protected` can only be accessed by components that directly inherit from it. ## Example ```slint,no-preview export component Example { in-out property min; in-out property max; protected function set-bounds(min: int, max: int) { root.min = min; root.max = max } public pure function inbound(x: int) -> int { return Math.min(root.max, Math.max(root.min, x)); } } ``` In the example above, `set-bounds` is a protected function that updates the `min` and `max` properties of the root component. The `inbound` function is a public, pure function that takes an integer `x` and returns the value constrained within the `min` and `max` bounds.