I'm working through this book right now and I'd like to give it a +1 as well. I worked through the untyped lambda calculus via Wikipedia a little while back but

I'm working through this book right now and I'd like to give it a +1 as well. I worked through the untyped lambda calculus via Wikipedia a little while back but it was a struggle. On the other hand this book's crystal clear exposition and exercises are like a breath of fresh air! Reading this first would have saved me a lot of time.