Implementation of "Complete and Easy Bidirectional Typechecking for Higher-Rank Polymorphism"

This implementation focusses on readability and being able to follow the paper while reading the code.

Use the synth function to synthesize a Type from an Expression. The process is traced through stdout, so that you can follow the rules invoked.

Basis of this implementation was the paper and implementations by Olle Fredriksson in Haskell and Albert ten Napel in TypeScript.