Recent Titles – Common Lisp ebook for free

I was thinking of reading a Lisp book. I checked the titles and decided to buy,
luckily, it’s freely provided in the Apress’ Practical Common Lisp page.
I doubt that it is done by mistake, because the e-book price is also indicated but anyway there is a free link to download it.



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It makes sense that the ebook for Practical Common Lisp is free, since the book is available from this website too: http://gigamonkeys.com/book/
Yeah that makes absolutely sense in that case. Thanks for the heads up.
That situation is expected I guess, because Peter wrote the book in a very collaborative-interactive fashion, posting each chapter and asked for feedback as the project went along. It was also quite an experience for me, since I read the book (and showered him with my questions and criticisms) as it was being written and shaped constantly. I can compare this experience and method of writing a high quality technical book only to ‘Real World Haskell’ which went further in terms of collaborative-interactive technical book authoring.
Anyway, did you read PCL? What are your impressions?