Notes and Codes on Mastering Ruby Closures A Guide to Blocks, Procs, and Lambdas from Benjamin Tao Wei Hao
This book is really nice and not long. I'm glad that I read it just after The Well Grounded Rubyist (TWGR). The last chapters of TWGR were all related to Procs, Lambdas, Blocks and functional programming, so it was really good to have some practice on this book.
This books make a good work teaching you the mechanics and tricks for Procs, Lambdas and Blocks. Also, the last chapter, is quite challenging. Implementing our own Lazy Enumerable got around my head and I'm sure I'll revisit this chapter with the Ruby Documentation in order to understand a little bit more about the mechanics behing it.
I will give this book 4.8/5. I feel that the last chapter could be explored a little bit more. Not necessarily going more deep, but expand it a little bit more. For every chapter there are exercises and you got the answers for each one if you want to take a look in case you are stuck.
It is a practical book, so you will get your hands dirty right at the first chapter. Not for beginners, though, since the author assume you have some Ruby knowledge beforehand.