sandbox.out

# cabal sandbox init
Writing a default package environment file to <ROOT>/sandbox.dist/cabal.sandbox.config
Creating a new sandbox at <ROOT>/sandbox.dist/sandbox
# cabal sandbox add-source
# cabal install
Resolving dependencies...
Configuring q-1.0...
Preprocessing library for q-1.0..
Building library for q-1.0..
Installing library in <PATH>
Installed q-1.0
# cabal run
message
# cabal run
In order, the following will be installed:
q-1.0 (reinstall)
message updated