[pjmlp]

You can inspect any expression, break into the debugger mid-execution, change the code, whatever code you feel like, redo the execution after applying the changes for example.

The ultimate redo-eval-loop, with almost zero downtime.

They are Jupyter notebooks on steroids.

[xkriva11]

...and start another debugger on any expression(s) you like. This is a super-useful feature.

https://files.pharo.org/web-images/carousel/fusion.gif