piping.js

/**
 * A debugging function that prints its arguments
 * @returns {String} an identifier that shows the name of this function
 */
function createConnFunc(name) {
  /* eslint-disable no-console */
  return function connFunnFunc(...args) {
    console.log(`${name}(${args.join(',')})`);
    return `conn_${name}`;
  };
}

const send_resp = createConnFunc('send_resp');
const put_resp_header = createConnFunc('put_resp_header');
const put_session = createConnFunc('put_session');
const put_resp_content_type = createConnFunc('put_resp_content_type');
const current_user = 'current_user_BOB';
const user = 'user_ALICE';
const location = 'location_OSLO';

console.log('\nALT1:');
const {bind, flow} = require('lodash');
const _ = bind.placeholder;
flow(
  bind(put_session, null, _, current_user, user),
  bind(put_resp_header, null, _, location, '/'),
  bind(put_resp_content_type, null, _, 'text/html'),
  bind(send_resp, null, _, 302, 'You are being redirected')
)('conn');

//////
// Trying to make it more compact ...
//////

console.log('\nALT2:');

// bind all but first argument - what should I call this?
// bindAllButFirstArgument is a tad bit long
const $$ = (...args) => bind(args[0], null, _, args.slice(1));

flow(
  $$(put_session, current_user, user),
  $$(put_resp_header, location, '/'),
  $$(put_resp_content_type, 'text/html'),
  $$(send_resp, 302, 'You are being redirected')
)('conn');

//////
// Third attempt at wrapping it up - renaming
//////

console.log('\nALT3:');

const pipe = (...args) => flow(...args);
pipe.prepare = fn => (...args) => bind(fn, null, _, args);

pipe(
  pipe.prepare(put_session)(current_user, user),
  pipe.prepare(put_resp_header)(location, '/'),
  pipe.prepare(put_resp_content_type)('text/html'),
  pipe.prepare(send_resp)(302, 'You are being redirected')
)('conn');