Learn Enough Ruby to Be Dangerous: Write Programs, Publish Gems, and Develop Sinatra Web Apps with Ruby by Michael Hartl

Author:Michael Hartl [Michael Hartl]
Language: eng
Format: epub, pdf, mobi
Publisher: Addison-Wesley Professional
Published: 2022-06-17T00:00:00+00:00

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states.reduce({}) { |lengths, state| lengths.merge({state => state.length}) }

See the documentation on merge for more information.)

As required, the result is the same as the imperative solution:

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$ ruby functional.rb . . . {"Kansas"=>6, "Nebraska"=>8, "North Dakota"=>12, "South Dakota"=>12} {"Kansas"=>6, "Nebraska"=>8, "North Dakota"=>12, "South Dakota"=>12}

Comparing the imperative and functional solutions in Listing 6.9, the advantages of reduce are not as clear as they were in the case of map and select. Indeed, a good argument can be made that the imperative solution is clearer.

Which method to use is a matter of taste. I’ve found that the more you program functionally, the more you want to do it, and there’s a strange sort of pleasure in using reduce to solve a problem in a single (logical) line. It’s also worth noting that reduce is a common technique among more advanced programmers, and among other things plays a key role in an important technique (called MapReduce) for dealing efficiently with large datasets.

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