Reading the article, I wonder if Shake could be used to generate Ninja files. It looks like it might be possible. The main "backend" improvements in Shake are things like concurrency reduction (pools in Ninja), hash-based rebuilding (available but undocumented in Ninja), and generated dependency rules. In such a setup, you'd use Shake for all your abstractions, and Ninja to execute the rules.
But I can see the appeal of Ninja files of something that allows one to avoid the GHC requirement in a build environment.
Though I've found Ninja to be more like something that needs to be generated from something else and less something you'd write. So maybe Ninja can be exactly that, kinda like build script assembly.
