xdebug exposes a gdbp interface which supports breakpoints, stepping, inspecting variables, etc. And you can use it with gdb or any GUI that supports gdbp, such

xdebug exposes a gdbp interface which supports breakpoints, stepping, inspecting variables, etc. And you can use it with gdb or any GUI that supports gdbp, such as macgdbp. EDIT: It does not expose a REPL though, which I suppose is what you meant?