Merge polytype and type data types
Monotype check
Progress on RankNTypes
More work on RankNTypes
Fix type synonyms when checking
Better error messages
Remove trace
More bug fixes
Better error messages during unification
Test cases pass again
General tidying, better approach to recursive functions with a top-level quantifier
Another test, and a TODO
More tests for RankNTypes, adding polytypes to type synonyms and data declaration
Polytypes in record fields, another example
Maybe monad
Another test
Fix name shadowing issue in bindings
Capture avoiding substitution during skolemization
Prevent skolem variables from escaping
Fix pattern matching for rank 2 constructors, and add an example