Use hpack's phrasing in dhall to write cabal files.
Install with cabal install hpack-dhall or install from
source.
There are two main reasons why you'd use hpack-dhall, convenience and safety.
Get the convenience of hpack. Don't bother to state what can be inferred or
defaulted, easing the burden of completing a package description by hand. For
example other-modules can be inferred by taking the set difference between
modules on disk and the set of exposed-modules.
Get the safety of dhall's programmable configuration: typed fields, safe imports and functions.
Another convenience is that files are easily formatted. The cabal file is formatted on write and the package dhall file can be formatted too with:
> dhall format --inplace package.dhall
We use hpack phrasing. The vocabulary of hpack's fields and values differs only slightly from cabal's properties. They're close Haskell packaging dialects.
This very package is described in
package.dhall
and produces
hpack-dhall.cabal
with the command:
> dhall-hpack-cabal
generated hpack-dhall.cabal
The generated cabal file can then inform both stack and cabal-install what modules to package into libraries, executables and test suites.
There is more you can do.
Value the dhall file as a way to produce the cabal file. If both files are be checked into source control but the cabal file gets ahead of the dhall file then it should be possible to get them in sync again.
