Heroku's engineering team writes about Rails and Ruby performance, Erlang operations, TLS, routing, and reliability.
HN commenters list it among notable company engineering blogs; the given comments give no opinion on it specifically.
> There is actually a lot of complexity to hashes in Ruby.
I agree here
> So if you construct a valid hash, then call three functions passing them the hash, you have no idea if the hash is still valid for the second and third functions without reading the code for all the preceding functions.
I don't find that to be true, even in the Rails codebase. You pass a hash to a function (method) and expect that it won't be mutated. If you're writing a method and you mutate a hash, you're expected to dup the argument so it won't be mutated. This is the convention. There are times when hashes are mutated, but generally that's reserved for methods who's purpose are to mutate its arguments.
Where Rails gets into trouble in its functional passing of hashes isn't in the mutability of the hashes, it's in the composability of the functions. I've never written about this problem before, so i'm not sure I have a great example but it's definitely a problem.
One example in rails is `url_for` it takes a hash argument. The problem is that there's multiple `url_for` methods that all do slightly different things. Some are needed for generating links in email, while some work in your views, and others are designed for you to use programmatically outside of a view context. One of the hardest things about this method is that one `url_for` can call another `url_for`. Since we can never be guaranteed the order of the calls it is really it makes things like having default values, or optional keys.…
These are some of the top sites' engineering blogs which I collected over a period of time - I removed those which have already been posted:
Google: http://googledevelopers.blogspot.com/ http://google-engtools.blogspot.com/ http://googleresearch.blogspot.com/
YouTube: http://youtube-eng.blogspot.com/
Baidu: http://usa.baidu.com/category/baidutechblog/
Yahoo: http://yahooeng.tumblr.com/ http://yahoodevelopers.tumblr.com/
Wikipedia (closest I could find): https://blog.wikimedia.org/c/technology/
Amazon: https://aws.amazon.com/blogs/aws/
Twitter: https://engineering.twitter.com/
eBay: http://www.ebaytechblog.com/
Microsoft: http://microsoftengineering.com
FourSquare: http://engineering.foursquare.com/
Apple (closest): https://developer.apple.com/
Paypal: https://www.paypal-engineering.com/ https://devblog.paypal.com/
Dropbox: https://blogs.dropbox.com/tech/
Edit: More (collected from this link: http://www.quora.com/What-are-the-top-startup-engineering-blogs):
Yelp: http://engineeringblog.yelp.com/
Quora: http://engineering.quora.com/
Yammer: http://eng.yammer.com/blog/
AirBnB: http://nerds.airbnb.com/
Square: https://corner.squareup.com/
Flickr: http://code.flickr.net/
Soundcloud: https://developers.soundcloud.com/blog/
Cloudera: http://blog.cloudera.com/blog/
Slideshare: http://engineering.slideshare.net/
Heroku: http://engineering.heroku.com/
Pinterest: http://engineering.pinterest.com/