djb's "redo" (implemented by apenwarr and others) is a minimalistic-almost-perfect implementation of incremental process.
TTBOMK, the only two things it doesn't do well are processes with multiple outputs (e.g., yacc has both .c and .h as output), and distinct output directories. Both can be worked around, but ... it's clunky. Other than that, it's ridiculously simple, extremely robust and generally awesome. Way better than Make at properly expressing dependencies.
But of course, gittup takes the prize - by virtue of watching the build process from inside, it doesn't need you to tell it about dependencies at all. It knows better than you do, and can thus do the fastest possible perfectly incremental builds.
TTBOMK, the only two things it doesn't do well are processes with multiple outputs (e.g., yacc has both .c and .h as output), and distinct output directories. Both can be worked around, but ... it's clunky. Other than that, it's ridiculously simple, extremely robust and generally awesome. Way better than Make at properly expressing dependencies.
But of course, gittup takes the prize - by virtue of watching the build process from inside, it doesn't need you to tell it about dependencies at all. It knows better than you do, and can thus do the fastest possible perfectly incremental builds.