Using ghcid

The ghcid package ghcid on GitHub is a reliable, helpful tool built on top of GHCi. It opens a project-aware REPL and automatically reloads your code on every save, so it saves you the step of manually :reloading. It also keeps the the top type error or warning in focus so that you don’t have to scroll up and try to find the top of the current batch as you work on fixing them. It’s really useful especially when you are refactoring or developing with holes at the type- or term-level.

You can see ghcid in action in the short video on ScopedTypeVariables.