Yes, this exactly! With OO-based PHP 7 codebases I work on, XDebug with the amazing Codebug client is brilliant. Breakpoint, then poke around the actual data structures within a running request, and see what happens!<p>When I&#x27;m working on functional codebases (our JavaScript is done in a very functional style, and I personally write Clojurescript and Wisp for my personal projects), I find printing the result of function calls completely sufficient, though I suppose one can consider a REPL not that conceptually different from an interactive debugger: in fact, Codebug and I think Komodo&#x27;s XDebug client actually give you a REPL to play with, set to the context of the given breakpoint