fp-library 0.17.0

A functional programming library for Rust featuring your favourite higher-kinded types and type classes.
Documentation 
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#![expect(clippy::unwrap_used, reason = "Tests use panicking operations for brevity and clarity")]

use {
	fp_library::{
		brands::*,
		functions::*,
	},
	std::thread,
};

#[test]
fn test_spawn_thread_with_send_fn() {
	let f = send_lift_fn_new::<ArcFnBrand, _, _>(|x: i32| x * 2);
	let handle = thread::spawn(move || f(21));
	assert_eq!(handle.join().unwrap(), 42);
}

#[test]
fn test_share_send_fn_across_threads() {
	let f = send_lift_fn_new::<ArcFnBrand, _, _>(|x: i32| x * 2);
	let f_clone1 = f.clone();
	let f_clone2 = f.clone();

	let handle1 = thread::spawn(move || f_clone1(10));
	let handle2 = thread::spawn(move || f_clone2(20));

	assert_eq!(handle1.join().unwrap(), 20);
	assert_eq!(handle2.join().unwrap(), 40);
	assert_eq!(f(30), 60);
}

#[test]
fn test_par_fold_map_in_thread() {
	let v = vec![1, 2, 3, 4, 5];
	let handle = thread::spawn(move || par_fold_map::<VecBrand, _, _>(|x: i32| x.to_string(), v));
	assert_eq!(handle.join().unwrap(), "12345".to_string());
}

#[derive(Clone, Copy, Debug, PartialEq)]
struct Sum(i32);

impl fp_library::classes::semigroup::Semigroup for Sum {
	fn append(
		a: Self,
		b: Self,
	) -> Self {
		Sum(a.0 + b.0)
	}
}

impl fp_library::classes::monoid::Monoid for Sum {
	fn empty() -> Self {
		Sum(0)
	}
}

#[test]
fn test_par_fold_map_concurrent_access() {
	let v = vec![1, 2, 3];
	let v_clone = v.clone();

	// Thread 1 uses par_fold_map on v_clone
	let handle1 =
		thread::spawn(move || par_fold_map::<VecBrand, _, _>(|x: i32| Sum(x * 2), v_clone));

	// Main thread uses par_fold_map on v
	let result2 = par_fold_map::<VecBrand, _, _>(|x: i32| Sum(x * 2), v);

	// Wait for thread 1
	let result1 = handle1.join().unwrap();

	assert_eq!(result1, Sum(12));
	assert_eq!(result2, Sum(12));
}

#[test]
fn test_par_map_in_threaded_context() {
	let v = vec![1, 2, 3, 4, 5];
	let handle = thread::spawn(move || par_map::<VecBrand, _, _>(|x: i32| x * 2, v));
	assert_eq!(handle.join().unwrap(), vec![2, 4, 6, 8, 10]);
}

// -- ArcCoyoneda concurrent access --

#[test]
fn test_arc_coyoneda_concurrent_lower_ref() {
	use fp_library::types::ArcCoyoneda;

	let coyo = ArcCoyoneda::<VecBrand, _>::lift(vec![1, 2, 3]).map(|x| x + 1).map(|x| x * 10);

	let handles: Vec<_> = (0 .. 4)
		.map(|_| {
			let coyo = coyo.clone();
			thread::spawn(move || coyo.lower_ref())
		})
		.collect();

	for handle in handles {
		assert_eq!(handle.join().unwrap(), vec![20, 30, 40]);
	}
}

#[test]
fn test_arc_coyoneda_shared_across_threads() {
	use {
		fp_library::types::ArcCoyoneda,
		std::sync::Arc,
	};

	let coyo = Arc::new(ArcCoyoneda::<VecBrand, _>::lift(vec![1, 2, 3]).map(|x| x * 2));

	let handles: Vec<_> = (0 .. 4)
		.map(|_| {
			let coyo = Arc::clone(&coyo);
			thread::spawn(move || coyo.lower_ref())
		})
		.collect();

	for handle in handles {
		assert_eq!(handle.join().unwrap(), vec![2, 4, 6]);
	}
}