An elegant Rails app which teaches a formal system core to computability. This site acts as a web interface for the lambda calculus gem I wrote. It features a tutorial page which interactively teaches the reader how lambda calculus works.
I’ve written a gem (Ruby’s name for a library) which constructs and evaluates lambda expressions. These are meaningful expressions from a mathematical system called lambda calculus, which forms the basis of functional programming languages. Using the gem, you can create lambda expressions in Ruby by typing them in a natural way. You can then tell Ruby to evaluate the expression, and it will print the result for you in the same natural notation. You can perform the evaluation step by step, or all at once.