Lambda calculus interpreter in Factor

Matthew Willis has implemented a lambda calculus interpreter in Factor. You can enter and evaluate lambda expressions. To start the evaluator, do:

  "lambda" require
  USE: lambda
  lint-boot lint

Now try evaluating some expressions. First, an identity function:

  ((x.x) 5)
OK:5

Something more complicated:

  (((x.(y.(y x))) 1) (x.x))
OK:1