divide Milner/Wand slide in two
higher-order example
bib item Wand87
typing rules, let polymorphism
skeleton for the examples section
first batch of examples
wording
example: covariance for type constructors
function type co- and contravariance
examples: fail covariance of lists, invariance assignments
example: type checking of record field fails
wording
use greek letters for type variables
move bussproofs to doc
remove parser combinator foobar
philosophy: initial