To my surprise, implies (and, coming in the next release, conflicts) are not available as option shorthand. Adding this would enable:

yargs.option('foo', {
  type: 'boolean',
  implies: 'bar',
  conflicts: 'baz'
});

// Same as:

yargs
  .boolean('foo')
  .implies('foo', 'bar')
  .conflicts('foo', 'baz');

Please let me know what you think. I'd be more than happy to submit a PR for this.