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Example usage of the reader monad.
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/** | |
* This short program will encrypt the user password | |
* and insert a new record into a mock database. | |
*/ | |
const Reader = require('fantasy-readers'); | |
const R = require('ramda'); | |
const crypto = require('crypto'); | |
// our mock database | |
const database = [ | |
{ email: 'user@example.org', password: 'e0538fd8f022bb3b139d72cf12766cb0e31690ff' }, | |
{ email: 'admin@example.org', password: '42c4fbf6fec201c66b82c97833b08d936d2cd526' } | |
] | |
// creates a statefull database connection | |
const connectTo = (db) => { | |
return { | |
insert: (doc) => db.push(doc), | |
get: (i) => db[i], | |
delete: (i) => db.splice(i, 1), | |
list: () => db | |
} | |
} | |
// some utility functions | |
const encrypt = (i) => crypto.createHash('sha1').update(i).digest('hex'); | |
const encPassword = R.evolve({password: encrypt}) | |
const getInput = () => ({ email: 'new@example.org', password: 'secret' }); | |
// this is how you access the db connection inside the reader | |
const save = (user) => { | |
return Reader.ask.map((db) => { | |
db.insert(user); | |
return db.list(); | |
}); | |
} | |
// the body of the program | |
const prog = R.pipe( | |
Reader.of, | |
R.map(encPassword), | |
R.chain(save) | |
); | |
// this is our db connection now | |
const dbCon = connectTo(database); | |
// this is how you pass the db connection in | |
const result = prog(getInput()).run(dbCon); | |
// show the output | |
console.log(result); |
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