"shell out" library that wraps around process
This is for actually shelling out (which is pretty "savage").
It tries to follow the same withBinaryFile ... like pattern you might use when you read files.
Other options that take the "we'll provide actual functions that are named similar to unix shell commands and do similar things without shelling out":
Those are probably more worthwhile looking into, but this library is for when there are functions that are unavailable in the above libraries or you are writing a haskell shim to manage a multiprocess application.
./mafia build
./mafia test