Functional Language Features: Iterators and Closures

Cairo’s design has taken strong inspiration from Rust, which itself has taken inspiration from many existing languages and techniques, and one significant influence is functional programming. Programming in a functional style often includes using functions as values by passing them in arguments, returning them from other functions, assigning them to variables for later execution, and so forth.

In this chapter, we won’t debate the issue of what functional programming is or isn’t but will instead discuss some features of Cairo that are similar to features in Rust and many languages often referred to as functional.

More specifically, we’ll cover:

• Closures, a function-like construct you can store in a variable
• Iterators, a way of processing a series of elements -->

We’ve already covered some other Cairo features, such as pattern matching and enums, that are also influenced by the Rust and the functional style. Because mastering closures and iterators is an important part of writing idiomatic, fast Cairo code, we’ll devote this entire chapter to them.