While we have demonstrated that our approach works,
we have not yet implemented all features of the build
system, and hope to do so over the next few months
This is a pretty major caveat. Almost damning in its significance, honestly. There are plenty of "works, but haven't quite implemented all of the old features" projects littering the world. I love that there are learnings here, and those should be seen as the most important artifact of any project. I do wish there were paths to get those learnings back to the old systems, though. :(
Table 1 in the paper looks promising, though. Let's hope their estimation is correct:
We implemented 5 a new build sys-
tem for GHC from scratch using Shake and our build abstractions
from §5. The new build system does not yet implement the full
functionality of the old build system, but we are currently address-
ing remaining limitations; nothing presents any new challenges or
requires changes to the build infrastructure.
Those guys are no amateurs, they work for Standard Chartered, one of the largest industrial users of Haskell that has been using Shake as its build system for a long time now. They have their own Haskell Compiler and >1 Million line Haskell codebase.
I'm not performing an ad hom. Nor do I want an appeal to authority. I fully wish them the best of luck in making a better build system, and I look forward to things they learn making it to other systems out there.
That line caught my attention pretty hard. It is mentioned in passing, and I have been part of many failed systems that were able to say the same thing. :) That is to say, I'm making my comment from experience. Not a desire for them to fail or give up.
