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Contents
# Strain
Implement the `keep` and `discard` operation on collections. Given a collection
and a predicate on the collection's elements, `keep` returns a new collection
containing those elements where the predicate is true, while `discard` returns
a new collection containing those elements where the predicate is false.
For example, given the collection of numbers:
- 1, 2, 3, 4, 5
And the predicate:
- is the number even?
Then your keep operation should produce:
- 2, 4
While your discard operation should produce:
- 1, 3, 5
Note that the union of keep and discard is all the elements.
The functions may be called `keep` and `discard`, or they may need different
names in order to not clash with existing functions or concepts in your
language.
## Restrictions
Keep your hands off that filter/reject/whatchamacallit functionality
provided by your standard library! Solve this one yourself using other
basic tools instead.
`apply` will let you pass arguments to a function, as will `fun.(args)`
## Running tests
Execute the tests with:
```bash
$ elixir strain_test.exs
```
### 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:
```elixir
# @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.
```elixir
# ExUnit.configure exclude: :pending, trace: true
```
For more detailed information about the Elixir track, please
see the [help page](http://exercism.io/languages/elixir).
## 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
87 entries across 87 versions & 1 rubygems