Added support for lambdas to Varvara's Bicycle
https://wiki.xxiivv.com/site/bicycle.html

Added a bit of information on the whole topic of anonymous functions and what one can do with them.
https://wiki.xxiivv.com/site/uxntal_lambdas.html

cc @dcreager That might be fun for you, I'm not sure how deep you're thinking about going into the functional side of things.