Example implementation of Algorithm W for Hindley-Milner type inference.
The PDF version of the tutorial is in subdirectory pdf.
You can load the code into ghci and play with it like this:
ghci AlgorithmW.lhs
On Debian 10, the following should work and create Transformers.pdf:
sudo apt install texlive
lhs2TeX AlgorithmW.lhs > AlgorithmW.tex
pdflatex AlgorithmW.tex
bibtex AlgorithmW.aux
pdflatex AlgorithmW.tex
mv AlgorithmW.pdf pdf/