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exercism fetch ruby accumulate

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:

And the operation:

Your code should be able to produce the collection of squares:

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.

Lisp specific: it's perfectly fine to use MAPCAR or the equivalent, as this is idiomatic Lisp, not a library function.

Advanced

It is typical to call #to_enum when defining methods for a generic Enumerable, in case no block is passed.

Here is an additional test you could add:

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def test_no_block_is_passed
  skip
  result = [1, 2, 3].accumulate
  assert_instance_of Enumerator, result
end

For installation and learning resources, refer to the exercism help page.

For running the tests provided, you will need the Minitest gem. Open a terminal window and run the following command to install minitest:

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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.

In order to run the test, you can run the test file from the exercise directory. For example, if the test suite is called hello_world_test.rb, you can run the following command:

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ruby hello_world_test.rb

To include color from the command line:

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ruby -r minitest/pride hello_world_test.rb

Source

Conversation with James Edward Gray II 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.