mk and Ninja (the target to which Kati compiles) appear to be almost equivalent to each other, except that mk has patterns ("here is how to compile any .c file into a .o file") and Ninja requires that each target be written explicitly ("here is how to compile foo.c into foo.o", once per file).
This is okay, because mk is meant to be written by humans and Ninja is meant to be a target for compilers like Kati and cmake.
This is okay, because mk is meant to be written by humans and Ninja is meant to be a target for compilers like Kati and cmake.