标签：
We‘ll learn how to take advantage of Ramda‘s automatic function currying and data-last argument order to combine a series of pure functions into a left-to-right composition, or pipeline, with Ramda‘s pipe function.
A simple example will take ‘teams‘ array and output the best score team‘s name. We use ‘R.sort‘, ‘R.head‘ and ‘R.prop‘ to get job done:
const teams = [ {name: ‘Lions‘, score: 5}, {name: ‘Tigers‘, score: 4}, {name: ‘Bears‘, score: 6}, {name: ‘Monkeys‘, score: 2}, ]; const getTopName = function(teams){ const sorted = R.sort( (a,b) => b.score > a.score, teams); const bestTeam = R.head(sorted); const name = R.prop(‘name‘, bestTeam); return name; } const result = getTopName(teams) console.log(result)
One thing in Ramda which is really cool that, for example, ‘R.sort‘ takes two arguements, if you don‘t passin the second arguement which is ‘teams‘, it will then return a function, so that it enable you currying function and take second arguement as param.
const teams = [ {name: ‘Lions‘, score: 5}, {name: ‘Tigers‘, score: 4}, {name: ‘Bears‘, score: 6}, {name: ‘Monkeys‘, score: 2}, ]; const getBestTeam = R.sort( (a,b) => b.score > a.score); const getTeamName = R.prop(‘name‘); const getTopName = function(teams){ const sorted = getBestTeam(teams); const bestTeam = R.head(sorted); const name = getTeamName(bestTeam); return name; } const result = getTopName(teams) console.log(result)
We will still get the same result.
Use ‘R.pipe‘ to chain function together
In functional programming or lodash (_.chain), we get used to write chain methods, in Ramda, we can use R.pipe():
const teams = [ {name: ‘Lions‘, score: 5}, {name: ‘Tigers‘, score: 4}, {name: ‘Bears‘, score: 6}, {name: ‘Monkeys‘, score: 2}, ]; const getBestTeam = R.sort( (a,b) => b.score > a.score); const getTeamName = R.prop(‘name‘); const getTopName = R.pipe( getBestTeam, R.head, getTeamName ); /* const getTopName = function(teams){ const sorted = getBestTeam(teams); const bestTeam = R.head(sorted); const name = getTeamName(bestTeam); return name; }*/ const result = getTopName(teams) console.log(result)
[Ramada] Build a Functional Pipeline with Ramda.js
标签：
原文地址：http://www.cnblogs.com/Answer1215/p/5801424.html
