Find and Map

Anthony M. Cook (2013)

Finds and returns the value of the block.

Usage

Put it in your Gemfile:

gem 'find_and_map'

Then you can include it on your own Enumerable object:

include FindAndMap

Or you can use the core extension directly the Gemfile:

gem 'find_and_map', require: 'find_and_map/core_ext'

Then you can use it like this:

{a: 1, b: 2}.find_and_map do |key, value|
  value if key == :a
end #=> 1

Background

I was looking for a way to simply find the first matching element in an enumerable and return a mapped result.

Using the same block above (in the Usage section) find returns [:a, 1] and map returns [1, nil]. But I want just the value, or even some other object based on it, but only that and nothing else.

This method finds the first match (like Enumerable#find) and then return the result of the block rather than the matching element (like Enumerable#map).

I don't like doing explict returns in the middle of loops, or nil checks if find fails, explicit breaks that alter the functionality of a standard iterator, and using compact after a map just seems excessive.

Here's some alternative ways of getting the desired result that violate the above constraints...

Using find:

{a: 1, b: 2}.find do |key, value|
  break value if key == :a
end

Using map:

{a: 1, b: 2}.map do |key, value|
  value if key == :a
end.compact

Contributing

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request