How to define higher-order functions in Rust

Higher-order functions (HOFs) in Rust are functions that can take other functions as parameters or return them as results, treating functions as first-class citizens. Rust supports defining functions using the `fn` keyword, and these functions can be stored in variables or passed as parameters, demonstrated with examples of named and anonymous functions. Anonymous functions, or closures, can capture their surrounding environment, enhancing their utility. The concept of returning functions involves more complexity due to Rust's memory management, requiring an understanding of lifetimes and borrowing, as illustrated by the `unapplied_binary_operator` function. This function uses references and the `move` keyword to manage variable ownership and lifetimes, ensuring safe memory usage. The article concludes by emphasizing the importance of HOFs in functional programming and their role in creating concise, maintainable code in Rust.