Rather to my surprise, I wrote a hundred lines of code between getting up and going to work this morning. I'm building an environment to help teach my students programming, which consists of panels where you can define functions on the left, and a repl-like thingy on the right where you can call functions, see their results, click on the results to expand a trace of computations, zoom in and out of the trace. Eventually I hope to be able to make an edit to a function and automatically rerun all the commands in the 'session', flagging any changes or errors. Automatic unit tests for a fraction of the effort. As of this morning, the left side is done. Screenshot: I'm going to start wiring up the right side next. (The repl and trace browser are already done as standalone commands.)