scsys_core/hkt/
applicative.rs

1/*
2    Appellation: applicative <mod>
3    Contrib: FL03 <jo3mccain@icloud.com>
4*/
5//! # Applicative
6//!
7//!
8use super::functor::Functor;
9use super::HKT;
10
11use super::containers::*;
12
13pub trait Applicative<U>: Functor<U> {
14    fn pure_(value: U) -> Self::T
15    where
16        Self: HKT<U, C = U>;
17    fn seq<F>(&self, fs: <Self as HKT<F>>::T) -> <Self as HKT<U>>::T
18    where
19        F: Fn(&<Self as HKT<U>>::C) -> U,
20        Self: HKT<F>;
21}
22
23#[allow(unused_macros)]
24macro_rules! applicative {
25    ($($t:ident),* $(,)?) => {
26        $(
27            applicative!(@impl $t);
28        )*
29    };
30    (@impl $t:ident) => {
31        impl<T, U> Applicative<U> for $t<T> {
32            fn pure_(value: U) -> Self::T {
33                $t::new(value)
34            }
35
36            fn seq<F>(&self, fs: <Self as HKT<F>>::T) -> $t<U>
37            where
38                F: Fn(&<Self as HKT<U>>::C) -> U,
39            {
40                let v = fs(self);
41                $t::new(v)
42            }
43        }
44    };
45}
46
47#[cfg(feature = "alloc")]
48applicative!(Arc, Box, Rc);
49
50impl<T, U> Applicative<U> for Option<T> {
51    fn pure_(value: U) -> Self::T {
52        Some(value)
53    }
54
55    fn seq<F>(&self, fs: <Self as HKT<F>>::T) -> Option<U>
56    where
57        F: Fn(&T) -> U,
58    {
59        match *self {
60            Some(ref value) => match fs {
61                Some(f) => Some(f(value)),
62                None => None,
63            },
64            None => None,
65        }
66    }
67}
68
69#[cfg(feature = "alloc")]
70impl<T, U> Applicative<U> for Vec<T> {
71    fn pure_(value: U) -> Self::T {
72        vec![value]
73    }
74
75    fn seq<F>(&self, fs: <Self as HKT<F>>::T) -> Vec<U>
76    where
77        F: Fn(&T) -> U,
78    {
79        let mut result = Vec::new();
80        for (i, f) in fs.into_iter().enumerate() {
81            let v = (f)(&self[i]);
82            result.push(v)
83        }
84        return result;
85    }
86}
scsys_core/hkt/applicative.rs

scsys_core/hkt/
applicative.rs
