How to Install¶

This sections documents how to install LH and its dependencies.

External Software Requirements¶

In order to use LiquidHaskell, you will need a SMT solver installed on your system. Download and install at least one of:

Note: The SMT solver binary should be on your PATH; LiquidHaskell will execute it as a child process.

Installing LiquidHaskell¶

LiquidHaskell itself is installed&enabled by adding it as a dependency in your project's .cabal file.

Just add liquidhaskell and liquid-base to the build-depends section of your .cabal file, as you would any other dependency.

This causes stack (or cabal) to automatically:

Install LiquidHaskell
Tell GHC to use LH during compilation
Display liquid type errors during compilation
Integrate LH with ghci, ghcid and all GHC compatible tooling for your favorite editor.

Examples¶

The following concrete examples show the LiquidHaskell plugin in action:

Example Project 1
Example Project 2 (uses Example Project 1 as a dependency)

You can use the .cabal, stack.yaml and cabal.project files in the sample packages to see how to write the equivalent files for your own codebase.

Liquid Dependencies¶

If you project depends on some well known library package foo (e.g. base or containers), then it's likely that the LiquidHaksell developers have annotated it with Liquid Types. You can use these annotations by adding the liquid-foo package to your build-depends.

Editor Integration¶

Since LiquidHaskell is implemented as a GHC plugin, you get to automatically reuse all ghc-based support for your editor as is. The sample packages include examples for vscode, vim and emacs.

Uninstallation¶

Just remove the liquid packages from your build-depends again, and GHC won't use LiquidHaskell anymore. You may also want to delete the .liquid directories placed alongside your source files (they contain debug information).

Other Options¶

Online Demo: For small projects without a .cabal file, you can paste your code into the online demo.