Just looks soooo promising! I don't think I can use it until conventional file target and dependencies are supported though. Right now everything's tasks (phonies) so conventional makefile rules like the following are impractical:
tic-tac-toe: tic.o tac.o toe.o
cc -o '$@' $^
%.o: %.c; cc -c $^
You might find checkexec useful to pair with just, it is basically a tool that only does the file-based dependency part of make: https://github.com/kurtbuilds/checkexec
