#1) start janet normally, work in the repl, encounter something to debug: (debug) # debug: # in thunk [repl] (tail call) on line 4, column 1 # nil # repl:5:> #2) because the -d flag was missing on start, debug is skipping back out into the repl. now i really DO want to debug here and now, without restarting the vm: (dyn *debug*) # => nil #3) we can just set the flag ourself and thus activate the debugger: (setdyn *debug* :anything_truthy) (debug) # debug: # in thunk [repl] (tail call) on line 2, column 1 # entering debug[1] - (quit) to exit # debug[1]:1:>