dypsilon · August 9, 2016 19:21 · Aug 9, 2016
diff --git a/reader_future.js b/reader_future.js
@@ -0,0 +1,62 @@
+/**
+ * This short program will encrypt the user password
+ * and insert a new record into a mock database.
+ */
+const Reader = require('fantasy-readers');
+const Future = require('fluture');
+const R = require('ramda');
+const crypto = require('crypto');
+
+// our mock database
+const database = [
+  { email: '[email protected]', password: 'e0538fd8f022bb3b139d72cf12766cb0e31690ff' },
+  { email: '[email protected]', password: '42c4fbf6fec201c66b82c97833b08d936d2cd526' }
+]
+
+// creates a statefull database connection
+const connectTo = (db) => {
+  return {
+    insert: (doc) => Future.of(db.push(doc)),
+    get: (i) => Future.of(db[i]),
+    delete: (i) => Future.of(db.splice(i, 1)),
+    list: () => Future.of(db)
+  }
+}
+
+// some utility functions
+const encrypt = (i) => crypto.createHash('sha1').update(i).digest('hex');
+const encPassword = R.evolve({password: encrypt})
+
+
+// utility function which makes it easier
+// to ask for some dependency
+// dependencies should reside in an object { dep: obj }
+const inject = R.curry((dep, f, reader) => {
+  return reader.chain((v) => {
+    return Reader.ask.map((env) => {
+      return f(env[dep], v);
+    });
+  });
+});
+
+// this is how you access the cb connection inside the reader
+const save = (db, user) => {
+  db.insert(user);
+  return db.list();
+}
+
+// the body of the program
+const handler = R.pipe(
+  R.map(encPassword),                          // Reader Object
+  inject('db', save),                          // Reader Future Error Object
+  R.map(R.map(R.map(R.dissoc('password'))))    // Reader Future Error Object
+);
+
+// this is our db connection now
+const dbCon = connectTo(database);
+
+const request = { email: '[email protected]', password: 'secret' };
+
+const result = handler(Reader.of(request))
+  .run({ 'db': dbCon }) // this is how you pass the db connection in
+  .fork(console.error, console.log); // now fork the future