fp_library/classes/
try_monoid.rs

1//! A trait for types that can be combined fallibly and have an empty value.
2//!
3//! This is similar to `Monoid`, but extends `TrySemigroup`.
4//!
5//! ### Examples
6//!
7//! ```
8//! use fp_library::{brands::*, classes::*, functions::*};
9//!
10//! let x = try_empty::<String>();
11//! assert_eq!(x, String::new());
12//! ```
13
14use super::{Monoid, TrySemigroup};
15
16/// A trait for types that can be combined fallibly and have an empty value.
17///
18/// This is similar to [`Monoid`], but extends [`TrySemigroup`].
19pub trait TryMonoid: TrySemigroup {
20	/// Returns the empty value.
21	///
22	/// ### Type Signature
23	///
24	/// `forall a. TryMonoid a => () -> a`
25	///
26	/// ### Returns
27	///
28	/// The empty value.
29	///
30	/// ### Examples
31	///
32	/// ```
33	/// use fp_library::{brands::*, classes::*, functions::*};
34	///
35	/// let x = String::try_empty();
36	/// assert_eq!(x, String::new());
37	/// ```
38	fn try_empty() -> Self;
39}
40
41impl<T: Monoid> TryMonoid for T {
42	fn try_empty() -> Self {
43		Monoid::empty()
44	}
45}
46
47/// Returns the empty value.
48///
49/// Free function version that dispatches to [the type class' associated function][`TryMonoid::try_empty`].
50///
51/// ### Type Signature
52///
53/// `forall a. TryMonoid a => () -> a`
54///
55/// ### Type Parameters
56///
57/// * `A`: The type of the value.
58///
59/// ### Returns
60///
61/// The empty value.
62///
63/// ### Examples
64///
65/// ```
66/// use fp_library::{brands::*, classes::*, functions::*};
67///
68/// let x = try_empty::<String>();
69/// assert_eq!(x, String::new());
70/// ```
71pub fn try_empty<A: TryMonoid>() -> A {
72	A::try_empty()
73}
fp_library/classes/try_monoid.rs

fp_library/classes/
try_monoid.rs
