For starters I’m not a super fan of interactive shell’s for non-system shells. I don’t see the point as much. When I first tried Devel::REPL I didn’t like it at all, compared to every other interactive shell I’ve used (with the notable exception of Oracle’s SQLPLUS, which is the worst shell ever) it was an unfriendly toy not worthy of mention. I couldn’t go up in history, there was no tab completion, and all in all the default output was ugly no colors or formatting.