Custom Setup to automate package modules discovery.
autopack is in early beta phase. ⚠️
Usually, when working on a Haskell project, you end up having lots of modules. During the development, you can add, remove or rename any of them. And this is fine unless you continuously need remembering to add, remove or rename the corresponding module line in the
.cabal file. Sometimes all you want is to make
Cabal dealing with it, so you won’t need to patch any files when performing any operations on modules. Good news, everyone! This project was created precisely to help to solve this particular issue.
autopack is a Haskell library that provides custom setup functions that discover all exposed
.hs files for your library from the
hs-source-dirs folders. It uses this information to prehook the list of identified modules into the
exposed-modules field of the library stanza of your package description.
You can use Cabal’s custom setup scripts to use this library in your project. In the next section, we are going to give detailed instructions on that.
For now, all you need to keep in mind to use
- It uses
hs-source-dirsfield to establish where to look up for modules.
- It can work only with
.hscextensions at the moment.
- It adds all discovered modules into
exposed-modulesof the library stanza.
- If there are already some modules in the
autopackwill concatenate lists.
How to use
First, make sure that you are using the Cabal version at least
2.0 in your
.cabal file. For example:
Now you need to change the
build-type field in your
package_name.cabal file to
Custom instead of the default
Then you have to add
custom-setup section before you defining your library stanza. It should have the
autopack dependency so you can use it in your
-setup custom-depends: base setup , autopack
And the final preparation. You should add the
Setup.hs module (or replace the default one) in the root directory of the package with the following content:
import Autopack (defaultMainAutoModules) main :: IO () = defaultMainAutoModulesmain
You are all set up now!
You can remove
exposed-module field from your
.cabal file completely, and
autopack will discover all the
.hs modules in your folders for you during the build.
Cabal does not currently provide the feature of automatic modules discovery, there are some workarounds for this process. One of them is this library —
autopack that uses
Cabal’s Setup feature to discover all modules during the pre-build stage of
Cabal. Another tool that provides it out-of-the-box is
hpack. It is the wrapper on
Cabal syntax via
YAML where there is no need to write modules explicitly. They are added to the
exposed-modules field of the
.cabal file during the YAML to
.cabal step of the tool work process. You may also be interested in
cabal-fmt – a non-official
.cabal files formatter than can optionally expand source directories during formatting.