With lisp REPLs one types in the IDE/editor having full highlighting, completions and code intelligence. Then code is sent to REPL process for evaluation. For example Clojure has great REPL tooling.
A variation of REPL is the REBL (Read-Eval-Browse Loop) concept, where instead of the output being simply printed as text, it is treated as values that can be visualized and browsed using graphical viewers.
Existing editors can already cover the runbooks use case pretty well. Those can be just markdown files with key bindings to send code blocks to shell process for evaluation. It works great with instructions in markdown READMEs.
The main missing feature editor-centric command like workflow I can imagine is the history search. It could be interesting to see if it would be enough to add shell history as a completion source. Or perhaps have shell LSP server to provide history and other completions that could work across editors?
Fish shell does this too
I wish someone would fork DeltaChat so I can keep using it as a client for "classic email".