Example usage of the reader monad.

/**

• 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);