exercism/elixir/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:

• 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.

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

Running tests

Execute the tests with:

$ elixir bob_test.exs

(Replace bob_test.exs with the name of the test file.)

Pending tests

In the test suites, all but the first test have been skipped.

Once you get a test passing, you can unskip the next one by commenting out the relevant @tag :pending with a # symbol.

For example:

# @tag :pending
test "shouting" do
  assert Bob.hey("WATCH OUT!") == "Whoa, chill out!"
end

Or, you can enable all the tests by commenting out the ExUnit.configure line in the test suite.

# ExUnit.configure exclude: :pending, trace: true

For more detailed information about the Elixir track, please see the help page.

Source

Conversation with James Edward Gray II https://twitter.com/jeg2

Submitting Incomplete Problems

It's possible to submit an incomplete solution so you can see how others have completed the exercise.