It's mostly how complete the API is and how consistent. For example: * Hash#merge takes a block for conflict resolution. I use this all the time for aggregating counts. * #sample * #unique * Everything has a change in place option by appending "!"

Also, chaining is extremely concise. e.g. "products.map(&:cost).sort.last"

I couldn't resist...

Your example could be improved by using "products.sort_by(&:cost).last"

I try to not use map because often there are methods that already implement filtering. Gotta love Ruby readability.

I think you need `products.sort_by(&:cost).last.cost` for the same result.

You’re correct!

one beautiful design decision ruby made really on was that every method would have the option to take a block of code when it was invoked. the code block gets passed to the method as a closure. this makes writing collection apis very pleasant, since so many of them involve passing in a single closure to operate on each element.