On Fri, May 8, 2015 at 12:12 PM, Dan Doel
vector generates a considerable amount of code using CPP macros.
And with regard to other mails, I'm not too eager (personally) to port that to template Haskell, even though I'm no fan of CPP. The code generation being done is so dumb that CPP is pretty much perfect for it, and TH would probably just be more work (and it's certainly more work to write it again now that it's already written).
Incidentally, if we really want to pursue the "get rid of CPP by building it into the GHC distro"... In recent years there've been a number of papers on "variational lambda-calculi"[1] which essentially serve to embed flag-based preprocessor conditionals directly into the language itself. One major benefit of this approach is that the compiler can then typecheck *all* variations of the code, rather than only checking whichever particular variation we happen to be compiling at the time. This is extremely useful for avoiding bitrot in the preprocessor conditionals. ...If we were to try and obviate the dependency on CPP, variational typing seems like a far more solid approach than simply reinventing the preprocessing wheel yet again. (The downside, of course, is making the Haskell spec significantly more complex.) [1] e.g., http://dl.acm.org/citation.cfm?doid=2398856.2364535 -- Live well, ~wren