Partial Application

Partial application is a functional programming technique where a function with multiple arguments is transformed into a new function with fewer arguments by fixing (or 'pre-applying') some of the original arguments. This creates a specialized version of the original function that can be called later with the remaining arguments. It is commonly used to create reusable function templates, simplify code, and enable function composition in languages that support higher-order functions.

Also known as: Partial Function Application, Currying (related but distinct), Function Binding, Pre-binding, Partial Eval

Why learn Partial Application?

Developers should learn partial application to write more modular, reusable, and declarative code, especially in functional programming paradigms. It is particularly useful in scenarios like event handling, configuration of functions, and creating utility functions where certain parameters are constant across multiple calls. For example, in JavaScript or Python, it can simplify callbacks or reduce boilerplate in data transformation pipelines.

Learning Resources

• docs: MDN Web Docs: Partial Application
• tutorial: Functional Programming in JavaScript: Partial Application
• book: Learn You a Haskell: Higher-Order Functions
• tutorial: Python functools.partial Tutorial
• video: Currying vs. Partial Application Video