I second Richard's observations about project-centered vs. compiler-centered workflows. I used to test all my code in ghci until cabal ended up installing two versions of the same package. Stack helped me to obtain a working Haskell environment again. But: While it is nicer to have the `real' code organized as a proper project, I still haven't figured out how to test individual modules in stack ghci without either loading the entire project or making an executable foo that imports the module and loading the executable with stack ghci project:exe:foo And I can't easily have a traditional GHC install alongside for testing since the haskell platform for the operating system uses a different base package. -- Olaf