-<!--
- To play around with a **typed lambda calculus**, which we'll look at later
- in the course, have a look at the [Penn Lambda Calculator](http://www.ling.upenn.edu/lambda/).
- This requires installing Java, but provides a number of tools for evaluating
- lambda expressions and other linguistic forms. (Mac users will most likely
- already have Java installed.)
--->
+There is also now a [library](/lambda_library) of lambda-calculus
+arithmetical and list operations, some relatively advanced.