[Functional Programming Monad] Modify The State Of A State Monad
Using put
to update our state for a given state transaction can make it difficult to modify a given state based on its previous value. In this lesson we will explore a means to lift specialized functions that can be used modify our state’s value. These specialized functions must have the same type in their input and output. We take a look at a construction helper named modify
that is used to remove the boilerplate of this type of construction. We also start to see how we can extend simple discrete stateful transactions to create other stateful transactions.
Modify state is apply a function to the original state to get new state:
// modifyState :: (s -> s) -> State s ()
const modifyState = fn => State(s => Pair(Unit(), fn(s)));
// modifyState :: (s -> s) -> State s ()
const modifyState = fn => State(s => Pair(Unit(), fn(s)));
const bubble = {
bubbles:
};
const add = x => y => x+ y;
console.log(
modifyState(mapProps({bubbles: add()}))
.runWith(bubble) // Pair( (), { bubbles: 41 } )
)
Of couse, we have the 'modify' function already in the library, so the code can be changed to:
const bubble = {
bubbles:
};
const add = x => y => x+ y;
console.log(
modify(mapProps({bubbles: add()}))
.runWith(bubble) // Pair( (), { bubbles: 41 } )
)
[Functional Programming Monad] Modify The State Of A State Monad的更多相关文章
- [Functional Programming] Read and Transform Values from a State ADT’s State (get)
Many times we need to access and transform state, either in part or in full, to be used when calcula ...
- [Functional Programming Monad] Combine Stateful Computations Using A State Monad
The true power of the State ADT really shows when we start combining our discrete, stateful transact ...
- [Functional Programming] Using ComposeK for both get State and modify State
We have State like this: const state = { cards: [ { id: "green-square", color: "green ...
- [Functional Programming Moand] Update The State Of A State Monad (put)
Stateful computations require the ability for their state to change overtime. We take a look on one ...
- Functional Programming without Lambda - Part 2 Lifting, Functor, Monad
Lifting Now, let's review map from another perspective. map :: (T -> R) -> [T] -> [R] accep ...
- [Functional Programming] Introduction to State, thinking in State
Recently, I am learning Working with ADT. Got some extra thought about State Monad. Basiclly how to ...
- Monad (functional programming)
In functional programming, a monad is a design pattern that defines how functions, actions, inputs, ...
- [Functional Programming Monad] Combine Stateful Computations Using Composition
We explore a means to represent the combination of our stateful computations using familiar composit ...
- [Functional Programming] Randomly Pull an Item from an Array with the State ADT (Pair)
Functor composition is a powerful concept that arises when we have one Functor nested in another Fun ...
- [Functional Programming] Transition State based on Existing State using the State ADT (liftState, composeK)
While sometimes outside input can have influence on how a given stateful transaction transitions, th ...
随机推荐
- MyBatis插入时候获取自增主键方法
方法一:(Oralce不支持这种写法) useGeneratedkeys 默认值为 false,含义:设置是否使用JDBC的getGenereatedKeys方法获取主键并赋值到keyProperty ...
- 跨域请求方式之Jsonp形式
在浏览器端才有跨域安全限制一说,而在服务器端是没有跨域安全限制的. 在两个异构系统(开发语言不同)之间达到资源共享就需要发起一个跨域请求. 而浏览器的同源策略却限制了从一个源头的文档资源或脚本资源与来 ...
- 嵌套循环连接(Nested Loops Joins)
The nested loops join, also called nested iteration, uses one join input as the outer input table(sh ...
- 解决 .htaccess 导致的403禁止访问
如果启用了mod_rewrite, 那么Options就一定要启用FollowSymLinks或者SymLinksifOwnerMatch, 否则会出现Fobidden页面禁止访问的错误. 于是把 O ...
- Python进阶:@property 动态属性
Python进阶:@property 动态属性 Python 动态属性的概念可能会被面试问到,在项目当中也非常实用,但是在一般的编程教程中不会提到,可以进修一下. 先看一个简单的例子.创建一个 Stu ...
- Flask实战第44天:完成前台注册功能
注册功能后端逻辑 用户注册要把注册的表单提交上来,因此,我要先对表单进行验证,编辑front.forms from apps.forms import BaseForm from wtforms im ...
- (转) HA的几种方案
数据库HA 一般把数据库层面的HA,和应用层面HA分开考虑 数据库一般采用数据库产品提供的HA方案,比如Oracle的RAC,mysql的集群,mongodb的replica set等 无HA的运 ...
- Python开发基础-Day2-流程控制、数字和字符串处理
流程控制 条件判断 if单分支:当一个“条件”成立时执行相应的操作. 语法结构: if 条件: command 流程图: 示例:如果3大于2,那么输出字符串"very good" ...
- hdu 6047 Maximum Sequence 贪心
Description Steph is extremely obsessed with “sequence problems” that are usually seen on magazines: ...
- html基础知识介绍
1 前端概要 前端三大利器 1.html 赤裸裸的人 2.css 穿上华丽的衣服 3.js 让人生动起来 2 HTML本质及在web程序中的作用 2.1 介绍 HTML 1.一套规则,浏览 ...