Re: [Caml-list] META file standards for ppx extensions

["Daniel Bünzli" <daniel.buenzli@erratique.ch>]

Le vendredi, 10 avril 2015 à 10:53, François Bobot a écrit :
> Just by curiosity, why do you want to separate the preprocessing from the compilation and not let
> ocaml do the piping? Is it for efficiency?

Maybe Thomas will have other comments to make since I personally stay away from the pre-processing cancer.  

But for one thing you can perfectly imagine doing a source pre-processing step before making a distribution, so that final users don't need to install the pre-processor you are using. Besides if you have a decent build system which finely tracks dependencies for minimal rebuilds you can perfectly imagine to not re-pre-process a file if only a *compilation* option changes.

In general it's better if the base compilation tools do not try to do too much/output many files in one go so that build systems can 1) trivially infer their outputs 2) reasonably rely on fs modification times to equate them with concrete content modification 3) be really in charge of composing the build pipeline.  

It's all about having a *composable* toolchain vs. inflexible monolithic black boxes.  

Best,

Daniel