I've written a few packages containing some extra functions for dealing with common types that reflect the way I like to use them (for instance, I prefer to treat Bson documents as maps, rather than lists of fields). I keep these packages in local source directories, not on Hackage.
I would like to introduce dependencies between these packages in their .cabal files, using cabal's build-depends system. But this leads to the following error (bson-docmap being a local module):
cabal: At least the following dependencies are missing:
bson-docmap >=0.0
Is it possible to point cabal to a local directory as an alternate repository?
My current workaround is to keep all my modules in a single local package, but I would prefer to break them apart if possible.
If you're using Cabal sandboxes then you can add a local Cabalized directory as a source
cabal sandbox add-source path/to/project/dir
After this point it'll be available for build-depends.
You may be able to create a ./cabal.project file with content like:
packages:
common/
backend/
frontend/
And then run $ cabal new-build all.
An example of this can be seen here: https://github.com/ElvishJerricco/reflex-project-skeleton/blob/11c1feb/cabal.project
来源：https://stackoverflow.com/questions/19622809/depending-on-a-local-package-in-cabal