Please use the cabal sandbox feature available in cabal >= 1.18 There is some overlap with the cabal sandbox add-source feature and using cabal-meta. You will probably want to try just using cabal sandbox with add-source and use cabal-meta when you have problems with that workflow.

cabal-meta is a cabal wrapper that facilitates:

• installing repos not on hackage (local or remote repos)
• specifying build flags
• ensuring that if possible, an install will succeed

Lets explain the last point: If you run this command, you can easily get a failure:

cabal install foo && cabal install bar

Whereas if you run this command it should almost always work:

cabal install foo bar

cabal-meta facilitates the second command: installing everything at once. This is very useful when you want cabal to install packages not on hackage. You need not worry about how cabal interprets your version, instead you let cabal easily interpret a location.

When invoked, cabal-meta looks for a file sources.txt. Each line of sources.txt is either a hackage package, a directory, or a github repo (which is cloned into a vendor/ directory). A directory is either a local cabal package or contains another sources.txt to recurse into.

cabal-meta automatically uses cabal-src-install (if you have it installed) unless you are using cabal-dev (--dev option). cabal-src-install is used to add local packages to your cabal package database: please see cabal-src documentation. Please note that this is done after the package install. If there is a failure anywhere along the way, cabal-src-install will not be used.

Run cabal-meta to see help output. Normal usage:

cabal-meta install

cabal-dev support:

cabal-meta --dev install

You can also supply arguments in an environment variable or a configuration file.

Controlling cabal-meta is done through sources.txt. sources.txt contains a repo location and optionally a branch name and build flags. Build flags start with a dash.

git://github.com/foo/bar ghc-7.6-compat -flag

darcs:http://darcs.net
darcs:http://hub.darcs.net/simon/darcsden

To build a Yesod application using the latest code, create a sources.txt in the project directory with:

./
https://github.com/yesodweb/yesod
https://github.com/yesodweb/shakespeare
https://github.com/yesodweb/persistent
https://github.com/yesodweb/wai

Now just run: cabal-meta install

To build a Yesod web application using my already downloaded source from github, I have a sources.txt in my project consisting of

./
sphinx -fone-one-beta
path/to/yesod/sources

./ refers to the current directory and thus your current project.

sphinx is a hackage package, and I have a build flag next to it that I don't have to worry about forgetting anymore. warning: a packge build flag will end up being applied to all packages

In the example above, path/to/yesod/sources contains a sources.txt with:

./hamlet
./persistent
./wai
./yesod

Each of these directories has a sources.txt listing several dirctories containing cabal packages that will be installed. Confused? It is just recursion, although we are interleaving IO :)