Created
January 2, 2020 13:33
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Simple example of nice, clean lens composition in ramda using a helper
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const nameLens = R.lensProp('name'); | |
const user = { | |
name: 'Joe', | |
age: 34, | |
isLoggedIn: true, | |
address: { | |
number: 123, | |
street: 'best' | |
} | |
}; | |
const lensCreator = lens => transform => user => ({ | |
get: () => R.view(lens, user), | |
set: (newName) => R.set(lens, newName, user), | |
transform: () => R.over(lens, transform, user) | |
}); | |
const transformAddress = input => `${input} street`; | |
const usersName = lensCreator(nameLens)(input => input.toLowerCase()); | |
let currentUsersNameLens = usersName(user); | |
console.log('1: ' + currentUsersNameLens.get()); | |
currentUsersNameLens = usersName(currentUsersNameLens.set('BoB')); | |
console.log('2: ' + currentUsersNameLens.get()); | |
currentUsersNameLens = usersName(currentUsersNameLens.transform()); | |
console.log('3: ' + currentUsersNameLens.get()); | |
const addressLens = R.lensProp('address'); | |
const streetLens = R.lensProp('street'); | |
const usersStreetLens = R.compose(addressLens, streetLens); | |
const usersStreet = lensCreator(usersStreetLens)(transformAddress); | |
const newUsersStreet = usersStreet(user).transform(); | |
console.log('addr: ', usersStreet(user).get()); | |
console.log('new addr: ', usersStreet(newUsersStreet).get()); |
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