FizzBuzz purely in Rust's trait system

栏目: IT技术 · 发布时间: 4年前

内容简介:We all know Rust's trait system is Turing complete, so tell me, why aren't we exploiting this??? Who needsHonestly, I was too preoccupied with the fact that I could to stop to think whether I actually should.Believe it or not,

trait_eval

We all know Rust's trait system is Turing complete, so tell me, why aren't we exploiting this??? Who needs const-fn when we've got a crate like this?!

Honestly, I was too preoccupied with the fact that I could to stop to think whether I actually should.

Believe it or not, I even wrote docs for this .

Example

Here's an eminently readable example where we play FizzBuzz at compile-time!

trait FizzBuzzType {
    fn show() -> String; // Don't worry about this -- it's just so we can print the result
}

struct Fizz;

impl FizzBuzzType for Fizz {
    fn show() -> String {
        "Fizz".to_string()
    }
}

struct Buzz;

impl FizzBuzzType for Buzz {
    fn show() -> String {
        "Buzz".to_string()
    }
}

struct FizzBuzz;

impl FizzBuzzType for FizzBuzz {
    fn show() -> String {
        "FizzBuzz".to_string()
    }
}

impl<T: Nat> FizzBuzzType for T
where
    T: Eval,
    <T as Eval>::Output: Display,
{
    fn show() -> String {
        format!("{}", T::eval())
    }
}

trait FizzBuzzEval: Nat {
    type Result: FizzBuzzType;
}

impl<T: Nat,
    Mod3: Nat,
    Mod5: Nat,
    ShouldFizz: Bool,
    ShouldBuzz: Bool,
    ShouldFizzBuzz: Bool,
    DidBuzz: FizzBuzzType,
    DidFizz: FizzBuzzType,
    DidFizzBuzz: FizzBuzzType> FizzBuzzEval for T
where
    T: Mod<Three, Result = Mod3> + Mod<Five, Result = Mod5>,
    Mod3: Equals<Zero, Result = ShouldFizz>,
    Mod5: Equals<Zero, Result = ShouldBuzz>,
    ShouldFizz: AndAlso<ShouldBuzz, Result = ShouldFizzBuzz>,
    (Fizz, T): If<ShouldFizz, Result = DidFizz>,
    (Buzz, DidFizz): If<ShouldBuzz, Result = DidBuzz>,
    (FizzBuzz, DidBuzz): If<ShouldFizzBuzz, Result = DidFizzBuzz>,
{
    type Result = DidFizzBuzz;
}

assert_eq!(<One as FizzBuzzEval>::Result::show(), "1");
assert_eq!(<Two as FizzBuzzEval>::Result::show(), "2");
assert_eq!(<Three as FizzBuzzEval>::Result::show(), "Fizz");
assert_eq!(<Four as FizzBuzzEval>::Result::show(), "4");
assert_eq!(<Five as FizzBuzzEval>::Result::show(), "Buzz");
assert_eq!(<Six as FizzBuzzEval>::Result::show(), "Fizz");
assert_eq!(<Seven as FizzBuzzEval>::Result::show(), "7");
assert_eq!(<Eight as FizzBuzzEval>::Result::show(), "8");
assert_eq!(<Nine as FizzBuzzEval>::Result::show(), "Fizz");
assert_eq!(<Ten as FizzBuzzEval>::Result::show(), "Buzz");

type Fifteen = <Three as Times<Five>>::Result;
assert_eq!(<Fifteen as FizzBuzzEval>::Result::show(), "FizzBuzz"); // !!!

Contributing

Please, for the love of God, don't use this crate. If you must contribute, open a PR.


以上所述就是小编给大家介绍的《FizzBuzz purely in Rust's trait system》,希望对大家有所帮助,如果大家有任何疑问请给我留言,小编会及时回复大家的。在此也非常感谢大家对 码农网 的支持!

查看所有标签

猜你喜欢:

本站部分资源来源于网络,本站转载出于传递更多信息之目的,版权归原作者或者来源机构所有,如转载稿涉及版权问题,请联系我们

知识发现

知识发现

史忠植 / 2011-1 / 59.00元

《知识发现(第2版)》全面而又系统地介绍了知识发现的方法和技术,反映了当前知识发现研究的最新成果和进展。全书共分15章。第1章是绪论,概述知识发现的重要概念和发展过程。下面三章重点讨论分类问题,包括决策树、支持向量机和迁移学习。第5章阐述聚类分析。第6章是关联规则。第7章讨论粗糙集和粒度计算。第8章介绍神经网络,书中着重介绍几种实用的算法。第9章探讨贝叶斯网络。第10章讨论隐马尔可夫模型。第11章......一起来看看 《知识发现》 这本书的介绍吧!

JSON 在线解析
JSON 在线解析

在线 JSON 格式化工具

正则表达式在线测试
正则表达式在线测试

正则表达式在线测试

HEX HSV 转换工具
HEX HSV 转换工具

HEX HSV 互换工具