co-promise

This does what you would expect and brings co a lot closer to what the async function proposal for es7 does.

var co = require('co-promise');

co(function* (err, value) {
}).
then(function() {
}).
catch(function() {
});

Important Notes

Normal co is likely faster so using co-promise only where you need to return a promise instead of a thunk (like to another api which expects a promise). This is generally okay since co-promise is only needed for the very top level generator the rest of the "yieldables" will use normal co functionality and not be wrapped with an extra layer of promises.