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# Accumulate
Implement the `accumulate` operation, which, given a collection and an
operation to perform on each element of the collection, returns a new
collection containing the result of applying that operation to each element of
the input collection.
Given the collection of numbers:
- 1, 2, 3, 4, 5
And the operation:
- square a number (`x => x * x`)
Your code should be able to produce the collection of squares:
- 1, 4, 9, 16, 25
Check out the test suite to see the expected function signature.
## Restrictions
Keep your hands off that collect/map/fmap/whatchamacallit functionality
provided by your standard library!
Solve this one yourself using other basic tools instead.
## Advanced
It is typical to call [#to_enum](http://ruby-doc.org/core-2.3.1/Object.html#method-i-to_enum) when defining methods for a generic Enumerable, in case no block is passed.
Here is an additional test you could add:
```ruby
def test_accumulate_when_block_is_deferred
skip
accumulate_enumerator = [1, 2, 3].accumulate
accumulated_result = accumulate_enumerator.each do |number|
number * number
end
assert_equal [1, 4, 9], accumulated_result
end
```
* * * *
For installation and learning resources, refer to the
[exercism help page](http://exercism.io/languages/ruby).
For running the tests provided, you will need the Minitest gem. Open a
terminal window and run the following command to install minitest:
gem install minitest
If you would like color output, you can `require 'minitest/pride'` in
the test file, or note the alternative instruction, below, for running
the test file.
Run the tests from the exercise directory using the following command:
ruby accumulate_test.rb
To include color from the command line:
ruby -r minitest/pride accumulate_test.rb
## Source
Conversation with James Edward Gray II [https://twitter.com/jeg2](https://twitter.com/jeg2)
## Submitting Incomplete Solutions
It's possible to submit an incomplete solution so you can see how others have completed the exercise.
Version data entries
77 entries across 77 versions & 1 rubygems