Reactive Principle: Every component accessible to the user should be able to present itself in a meaningful way for observation and manipulation.
The quote above is worth repeating.
We think of Morphs and “data objects” as able to present themselves to be inspected, but Smalltalk’s runtime state is also presentable.
| • Inspecting the Unexpected: | ||
| • The Debugger: | ||
| • Halt!: |