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We are working towards making exercises stand-alone. That is to say: no more generating READMEs on the fly. This will give maintainers more control over each individual exercise README, and it will also make some of the backend logic for delivering exercises simpler. The README template uses the Go text/template package, and the default templates generate the same READMEs as we have been generating on the fly. See the documentation in [regenerating exercise readmes][regenerate-docs] for details. The READMEs can be generated at any time using a new 'generate' command in configlet. This command has not yet landed in master or been released, but can be built from source in the generate-readmes branch on [configlet][]. [configlet]: https://github.com/exercism/configlet [regenerate-docs]: https://github.com/exercism/docs/blob/master/maintaining-a-track/regenerating-exercise-readmes.md
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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.
Elm Installation
Refer to the Exercism help page for Elm installation and learning resources.
Writing the Code
The first time you start an exercise, you'll need to ensure you have the appropriate dependencies installed.
$ npm install
Execute the tests with:
$ npm test
Automatically run tests again when you save changes:
$ npm run watch
As you work your way through the test suite, be sure to remove the skip <|
calls from each test until you get them all passing!
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.