[benbataille]

While not being exactly about type theory like Pierce books (you can't waste your money on those), I really like the part about types in "The Implementation of Functional Programming Languages" by Peyton Jones (the chapters about type system are written by Peter Hancock). It's seen mostly from a technical point of view. The book notably contains a fully explained implementation of a type checker.

You can check it online while waiting for the Pierson ones: http://research.microsoft.com/en-us/um/people/simonpj/papers...

[benbataille]

Sorry for the ambiguity. It's certainly not a waste of money. I found "Types and Programming Languages" really good (for whatever that means, I'm far from being an authority in the subject). It seems to be wildly used as a textbook and is a reference in the subject. While I didn't read it, I expect the second one to be in the same vein.

[TrevorFancher]

By "can't waste your money" do you mean that buying them is not a waste of money or that I shouldn't waste my money on them?

Also, thanks for the link to the article.