Pjiwm/functional-rust

A Rust library for functional programming, providing function composition, currying, and higher-order functions. This crate can be compiled on nightly Rust.

functional_rs

functional_rs is an experimental crate that brings functional programming concepts to Rust using Nightly features. By implementing Fn on structs, it enables function composition, currying, and other higher-order functional programming patterns. The goal is to keep the syntax as concise as possible, making functional patterns easy to use without cluttering the code.

This crate is designed for Nightly Rust and uses experimental features, so it’s not stable yet.

Example

use functional_rs::{c, f, ComposableFn};
use std::str::FromStr;

fn main() {
    let from_str = i32::from_str;
    let parse_or_zero = |result: Result<i32, <i32 as FromStr>::Err>| result.unwrap_or(0);

    // Currying with composition
    let add = c!(|a: i32, b: i32| a + b);
    let add_10_from_str = f!(from_str) >> f!(parse_or_zero) >> f!(add(10));

    // Using the composed function
    assert_eq!(add_10_from_str("4"), 14); // (4 -> parse -> add 10) = 14
    assert_eq!(add_10_from_str("not a number"), 10); // invalid input -> default 10
}