Haskell cabal compile .js during build

Question

Let's say I'm building a web application with haskell as both server-side and client-side code. During the build phase, I want to compile server-side code with ghc and client-side code with some haskell to js transpiler.

The haskell transpiler tools expose an executable that I need to feed with .hs files and it will compile to .js files. How do I specify in cabal to run external programs during the build phase? I can see, that the UserHooks field buildHook has the return type IO(), so I can theoretically probably use for example shelly library to execute shell code to run the transpiler, but I don't know if this is the cleanest solution.

Answer 1

Here's a post i wrote about solving the same problem.

It's usually a bad idea to use custom Setup files since there is no way to handle dependencies for it, and unless you install these dependencies first you can't even sdist.

I find it works well to have an optional command line option that precompiles code when the webserver starts.

Another option is to have a makefile that compiles both.