Hi -- thanks for the report. However, you should be using plai-typed, not plai.
You can find plai-typed here: http://cs.brown.edu/courses/cs173/2012/lang/ If you install and run with plai-typed instead of plai, you will find that the colon-endowed syntax works just fine (I just tested the very code you pasted). Note that the book section you point to also says "plai-typed". Thanks, Shriram ____________________ Racket Users list: http://lists.racket-lang.org/users
