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Ramda stuff
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var R = require('ramda'); | |
var states = [ | |
{symbol: 'CT', name: 'Connecticut', pop: 3574097}, | |
{symbol: 'ME', name: 'Maine', pop: 1328361}, | |
{symbol: 'MA', name: 'Massachusetts', pop: 6547629}, | |
{symbol: 'NH', name: 'New Hampshire', pop: 1316470}, | |
{symbol: 'RI', name: 'Rhode Island', pop: 1052567}, | |
{symbol: 'VT', name: 'Vermont', pop: 623741}, | |
]; | |
var notSmall = (state) => state.pop >= 2000000; | |
R.reduce((accum, state) => notSmall(state) ? | |
R.assoc(state.symbol, state.pop, accum) : | |
accum, | |
{}, states); //=> {"CT": 3574097, "MA": 6547629} | |
R.pipe( | |
R.filter(notSmall), | |
R.map(R.props(['symbol', 'pop'])), | |
R.fromPairs)(states) //=> {"CT": 3574097, "MA": 6547629} | |
R.reduce((accum, state) => notSmall(state) ? R.assoc(state.symbol, state.pop, accum) : accum, {}, states); | |
R.pipe( | |
R.filter(notSmall), | |
R.map(R.props(['symbol', 'pop'])), | |
R.fromPairs)(states); | |
R.fromPairs(R.map(R.props(['symbol', 'pop']), R.filter(notSmall, states))) | |
R.fromPairs([[ 'CT', 3574097 ]]) | |
R.pipe(R.props(['symbol', 'pop']), R.fromPairs)([ 'CT', 3574097 ]); | |
R.map(R.pipe(R.props(['symbol', 'pop']), R.fromPairs), R.filter(notSmall, states)); | |
// Path | |
R.path(['a', 'b'], {a: {b: 2}}); | |
// Combining functions | |
const isEven = x => x % 2 === 0 | |
R.find(isEven, [1, 2, 3, 4]) | |
R.find(R.complement(isEven), [1, 2, 3, 4]) | |
R.filter(isEven, [1, 2, 3, 4]) | |
R.filter(R.complement(isEven), [1, 2, 3, 4]) | |
// Both/ Either/ Curry | |
var wasBornInCountry = R.curry((country, person) => person.birthCountry === country) | |
wasBornInCountry('GB') //=> [Function] | |
wasBornInCountry('GB', {birthCountry: 'GB'}) //=> true | |
wasBornInCountry('GB')({birthCountry: 'GB'}) //=> true | |
wasBornInCountry('GB')({birthCountry: 'IE'}) //=> false | |
var wasNaturalized = person => Boolean(person.naturalizationDate) | |
wasNaturalized({birthCountry: 'IE', naturalizationDate: '2014-01-01'}) //=> true | |
wasNaturalized({}) //=> false | |
var isOver18 = person => person.age >= 18 | |
isOver18({age: 17}) //=> false | |
isOver18({age: 18}) //=> true | |
isOver18({age: 19}) //=> true | |
var isCitizen = R.curry((country, person) => R.either(wasBornInCountry(country), wasNaturalized)(person)) | |
isCitizen('GB')({birthCountry: 'IE', naturalizationDate: '2014-01-01'}) | |
isCitizen('GB', {birthCountry: 'IE', naturalizationDate: '2014-01-01'}) | |
isCitizen('GB', {birthCountry: 'GB'}) | |
var isEligibleToVote = (country, person) => R.both(isCitizen(country), isOver18)(person) | |
isEligibleToVote('GB', {birthCountry: 'GB', age: 19}) //=> true | |
isEligibleToVote('GB', {birthCountry: 'GB', age: 17}) //=> false | |
isEligibleToVote('GB', {birthCountry: 'IE', age: 19}) //=> false | |
isEligibleToVote('GB', {birthCountry: 'IE', age: 19, naturalizationDate: '2014-01-01'}) //=> true | |
var isEligibleToVoteGB = R.curry(isEligibleToVote)('GB'); | |
isEligibleToVote('GB', {birthCountry: 'GB', age: 19}) //=> true | |
isEligibleToVoteGB({birthCountry: 'IE', age: 19}) //=> false | |
isEligibleToVoteGB({birthCountry: 'IE', age: 19, naturalizationDate: '2014-01-01'}) //=> true | |
var gt10 = x => x > 10; | |
var even = x => x % 2 === 0; | |
var f = R.either(gt10, even); | |
f(101); //=> true | |
f(8); //=> true | |
f(7) //=> false | |
// Define a curried greater than function | |
var gt = R.curry((x, n) => n > x); | |
gt(10, 11) //=> true | |
gt(10, 10) //=> false | |
gt(10, 9) //=> false | |
// Redefine the greater than 10 function by only supplying the first argument | |
// to our curried greater than function which will return a new function which | |
// accepts a single argument (the number to test) | |
var gt10 = gt(10) | |
gt10 | |
var f2 = R.either(gt10, even); | |
f2(101); //=> true | |
f2(8) //=> true | |
f2(7) //=> false | |
var f3 = R.both(gt10, even); | |
f3(101); //=> false | |
f3(8) //=> false | |
f3(7) //=> false | |
f3(102); //=> true |
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