Smalltalk has had this too since 1980 or earlier. The Smalltalk approach generally involves changing the code for a named method and then restarting either the

Smalltalk has had this too since 1980 or earlier. The Smalltalk approach generally involves changing the code for a named method and then restarting either the method or a code block inside the method. Coupled with Smalltalk's flexible doesNotUnderstand error handling for when methods are not implemented, coding in the Smalltalk debugger is phenomenal for top-down programming where essentially you keep pushing deeper into a code base you are creating on the fly.