I see why you might link to the page you did since it has some additional information, and even provides a link to the more recent edition, but be aware that this is an old version of PLAI that has been updated as recently as 2012 [0].
Furthermore, the cs173 class at Brown now uses a different book, Programming and Programming Languages [1], that was updated as recently as 2014. It's very much in the same spirit, but uses Pyret instead of plai-typed.
Another thing to note is that cs173 had a MOOC-like online offering in 2012, and the videos are still available [2].
[0] http://cs.brown.edu/courses/cs173/2012/book/