There is now a [library](/lambda_library) of lambda-calculus arithmetical and list operations, some relatively advanced.
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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.)
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