My consistent experience with OCaml has been that the build systems are
fiddly and hard to work with, but I've never seen a discussion of why this
is so (as opposed to problems with specific build tools). Supposing you
were to start from scratch and develop a new build system in a bottom up
manner, starting with a set of libraries and utilities and working your way
up to a framework or dsl, what would the difficult steps be?

martin