Functions

Introduction

Functions are a core concept in Script-Fu, providing the means to encapsulate logic, enable code reuse, and structure your scripts effectively. With functions, you can create modular, maintainable scripts that handle a wide range of tasks, from basic operations to advanced workflows in GIMP.

This section serves as an introduction to functions in Script-Fu and lays the groundwork for understanding their types, definitions, and uses. Subsequent sections will delve deeper into specific function types and their unique capabilities.

Why Functions Matter

Functions play a pivotal role in Script-Fu for several reasons:

Code Reusability: Avoid repetition by encapsulating logic into reusable components.
Modularity: Break down complex tasks into smaller, manageable pieces.
Dynamic Behavior: Accept parameters to handle various inputs or adapt to different situations.
Higher Abstraction: Simplify logic by focusing on “what” a function does rather than “how” it does it.

Overview of Function Types

Script-Fu offers a variety of function constructs, each suited to specific use cases:

Named Functions
These are standard functions defined with define. They form the backbone of most scripts.
```
(define (square x)
  (* x x))
```
Anonymous Functions
Also known as lambda functions, these are unnamed functions defined inline for one-off use.
```
(lambda (x) (* x x))
```
Higher-Order Functions
Functions that take other functions as arguments or return functions as results, enabling powerful abstractions like mapping, filtering, and reducing.
```
(map (lambda (x) (* x x)) '(1 2 3 4))  ; Returns (1 4 9 16)
```

General Syntax for Functions

Functions in Script-Fu have a simple and consistent syntax:

(define (function-name parameter1 parameter2 ...)
  body-expression)

function-name: The name of the function.
parameter1, parameter2, ...: The arguments the function takes.
body-expression: The logic executed when the function is called.

Example:

(define (add x y)
  (+ x y))

(add 3 5)  ; Returns 8