fp_library/classes/
pointed.rs

1//! Pointed type class.
2//!
3//! This module defines the [`Pointed`] trait, which represents a context that can be initialized with a value.
4
5use crate::{Apply, kinds::*};
6
7/// A type class for types that can be constructed from a single value.
8///
9/// `Pointed` represents a context that can be initialized with a value.
10pub trait Pointed: Kind_c3c3610c70409ee6 {
11	/// The value wrapped in the context.
12	///
13	/// This method wraps a value in a context.
14	///
15	/// ### Type Signature
16	///
17	/// `forall a. Pointed f => a -> f a`
18	///
19	/// ### Type Parameters
20	///
21	/// * `A`: The type of the value to wrap.
22	///
23	/// ### Parameters
24	///
25	/// * `a`: The value to wrap.
26	///
27	/// ### Returns
28	///
29	/// A new context containing the value.
30	///
31	/// ### Examples
32	///
33	/// ```
34	/// use fp_library::classes::pointed::Pointed;
35	/// use fp_library::brands::OptionBrand;
36	///
37	/// let x = OptionBrand::pure(5);
38	/// assert_eq!(x, Some(5));
39	/// ```
40	fn pure<'a, A: 'a>(
41		a: A
42	) -> Apply!(
43		brand: Self,
44		signature: ('a, A: 'a) -> 'a,
45	);
46}
47
48/// The value wrapped in the context.
49///
50/// Free function version that dispatches to [the type class' associated function][`Pointed::pure`].
51///
52/// ### Type Signature
53///
54/// `forall a. Pointed f => a -> f a`
55///
56/// ### Type Parameters
57///
58/// * `Brand`: The brand of the context.
59/// * `A`: The type of the value to wrap.
60///
61/// ### Parameters
62///
63/// * `a`: The value to wrap.
64///
65/// ### Returns
66///
67/// A new context containing the value.
68///
69/// ### Examples
70///
71/// ```
72/// use fp_library::classes::pointed::pure;
73/// use fp_library::brands::OptionBrand;
74///
75/// let x = pure::<OptionBrand, _>(5);
76/// assert_eq!(x, Some(5));
77/// ```
78pub fn pure<'a, Brand: Pointed, A: 'a>(
79	a: A
80) -> Apply!(
81	brand: Brand,
82	signature: ('a, A: 'a) -> 'a,
83) {
84	Brand::pure(a)
85}
fp_library/classes/pointed.rs

fp_library/classes/
pointed.rs
