Reddit reviews Ruby Under a Microscope: An Illustrated Guide to Ruby Internals

A great book for learning about the inner workings of Ruby is Ruby Under The Microscope:
http://www.amazon.com/Ruby-Under-Microscope-Illustrated-Internals/dp/1593275277

It walks through the the whole MRI implementation, the parser, lexer, byteocdeo, YARV etc. along with some of the C source code to give you a picture of how Ruby actually works internally. I believe there's some chapters about Jruby and Rubinius as well but I haven't read those yet.

A book called Ruby Under a Microscope is a great start to learning about the MRI internals.

1. Ruby has symbols that are used in place of most strings. If you have a :word_symbol, that is a globally unique identifier. Anywhere you see the exact phrase :word_symbol it's the same as all of the others. Ruby inherently gains a lot of performance from this that would otherwise be from immutable strings, without losing the easy mutability of strings.
   
   
2. IIRC, hashes keys for strings use a memory copy as an immutable string, which is the other major performance gain. However, the key lookup still has to do a string comparison, which (again IIRC) are optimized for small comparison sequences, I think under 32 length.
   
   >> string_key = "word"
   => "word"
   >> hash = { string_key => 'whatever' }
   => {"word"=>"whatever"}
   >> string_key = 'word2'
   => "word2"
   >> hash # no change to the key
   => {"word"=>"whatever"}
   
   If you're curious about how Ruby works under the hood, this book is exceptional: https://www.amazon.com/Ruby-Under-Microscope-Illustrated-Internals/dp/1593275277. It's a few years old so it might be a bit out of date with the garbage collection in particular, but it's hugely helpful!

Ruby under a Microscope is good, if you want a better understanding of Ruby internals. http://www.amazon.com/Ruby-Under-Microscope-Illustrated-Internals/dp/1593275277

> If you're curious about how Ruby works under the hood, this book is exceptional: https://www.amazon.com/Ruby-Under-Microscope-Illustrated-Internals/dp/1593275277. It's a few years old so it might be a bit out of date with the garbage collection in particular, but it's hugely helpful!

Thanks for the recommendation! Not sure if I will get around to read it (reading POODR by Sandi Metz right now) but I put it on my Amazon list.

I pretty recommend this book: http://createyourproglang.com/, and this series: https://hokstad.com/compiler


If you want something more advanced you can read the famous https://www.amazon.com.br/Ruby-Under-Microscope-Illustrated-Internals/dp/1593275277 to understand how a language works behind scenes. Understanding Computation is also good too.