There's a thread about lisp machines on twitter that I really enjoyed:
https://twitter.com/RainerJoswig/status/1213484071952752640
• All commands have uniform introspection
• The console contains 'live views', not dead text
• Every app (activity) has an embedded REPL which exposes all the commands of that activity. The commands can also be invoked via menus/buttons and each command is just a function
• You can jump to source for any of these functions and live edit it