zoukankan      html  css  js  c++  java
  • [Javascript] Multiply Two Arrays over a Function in JavaScript

    Just like the State ADT an Array is also an Applicative Functor. That means we can do the same tricks with liftA2 with Array that we have been doing with State.

    While the Applicative aspect of State allows use to combine multiple stateful transitions over a function, Array allows us to create a new Array that contains the results of calling every permutation of each element in two arrays over a function. We will use this ability to pull from two separate locations in our AppStateand generate an Array of Cards.

    liftA2 from crocks.js "Ever see yourself wanting to map a binary or trinary function, but map only allows unary functions? Both of these functions allow you to pass in your function as well as the number of Applicatives (containers that provide bothof and apfunctions) you need to get the mapping you are looking for."

    lift from Ramda.js "lifts" a function of arity > 1 so that it may "map over" a list, Function or other object that satisfies the FantasyLand Apply spec.

    // Crocks.js
    
    const buildCard = curry((color, shape) => console.log(color, shape) || ({
        id: `${color}-${shape}`,
        color,
        shape
    }));
    // buildCards :: [String] -> [String] -> [Card]
    const buildCards = liftA2(buildCard);
    
    
    // Ramda.js
    
    const build = lift(buildCard);

     --- 

    const {prop,assoc, pick, State, identity, omit, curry, filter, converge,map, composeK, liftA2, equals, constant,option, chain, mapProps, find, propEq, isNumber, compose, safe} = require('crocks');
    const  {get, modify, of} = State; 
    const {lift} = require('ramda');
    
    const state = {
        colors: [ 'orange', 'green', 'blue', 'yellow' ],
        shapes: [ 'square', 'triangle', 'circle' ]
      };
    
    const getState = (key) => get(prop(key))
    const getColors = () => getState('colors').map(option([]));
    const getShapes = () => getState('shapes').map(option([]));
    
    const buildCard = curry((color, shape) => console.log(color, shape) || ({
        id: `${color}-${shape}`,
        color,
        shape
    }));
    // buildCards :: [String] -> [String] -> [Card]
    const buildCards = liftA2(buildCard);
    const generateCards = converge(
        liftA2(buildCards),
        getColors,
        getShapes
    )
    console.log(
        generateCards()
            .evalWith(state)
    )
    
    const build = lift(buildCard);
    console.log('build', build([1,2,3], ['c', 'd']))
  • 相关阅读:
    SSM整合初级 简单的增删改查
    初始SpringMVC
    初始Spring MVC
    Web Service简介
    Quartz框架 实现任务调度
    搭建james邮件服务器
    使用Jdbc Template的基本操作步骤
    spring AOP四种实现方式
    Struts2数据校验
    Struts2 与Servlet API解耦,耦合的访问方式
  • 原文地址:https://www.cnblogs.com/Answer1215/p/10277748.html
Copyright © 2011-2022 走看看