Liquid Haskell

This repository accompanies the MuniHac 2020 Workshop on Liquid Haskell.

We are going to use the new Liquid Haskell GHC plugin.

If you want to follow along with the workshop, please clone this repository and try to build it:

• You need the z3 theorem prover installed and in your PATH. (This is a non-Haskell dependency, so you have to install it separately.)

• If you can, use GHC 8.10.2. GHC 8.10.1 should also work, but if you want to use ghcide with Liquid Haskell properly, you will need 8.10.2.

• I will use cabal, but the package should also be buildable with stack.

• If the package builds successfully, then as part of the build output for the Tutorial module in this package you should see the text LIQUID: SAFE (3 constraints checked). If you can see this, the plugin seems to be working correctly.

• Unfortunately, Windows support for plugins is known to be unreliable. If you are on Windows, the above may just not work. You may still have the option to install the liquidhaskell package on your system, giving you an executable called liquid, and running liquid on Tutorial.hs via the command line.