[racket] Behaviour with read-only files

On Nov 17, 2011, at 1:47 PM, John Clements wrote:

> Suppose you run a big-bang program that puts a dot on the screen every time you press a key.  Now suppose it runs for 1K steps and halts. The user sees that the window is frozen, but probably won't figure out that the way to un-freeze it is to go to the stepper window and advance past the end of the currently-computed steps.

Perhaps 'universe' should have a 'stepper' entry point so that it can signal to programmers that it is waiting for stepper input. -- Matthias