From the Chandler email list...
In September, Hamish Harvey described some of the neat things about
Haystack, including UI continuations. (Harvey's message was posted Fri, 26
Sep 2003; there's an article describing Haystack's continuations at
I just wanted to add a reference to a tutorial article on continuations
using Python: "Continuations Made Simple and Illustrated" by Denys Duchier
Posted to implementation by Patrick Logan on 1/4/04; 4:18:42 PM