78 lines
3.4 KiB
Markdown
78 lines
3.4 KiB
Markdown
# Hello World
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Write a function that greets the user by name, or by saying "Hello, World!" if no name is given.
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["Hello, World!"](http://en.wikipedia.org/wiki/%22Hello,_world!%22_program) is the traditional first program for beginning programming in a new language.
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**Note:** You can skip this exercise by running:
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exercism skip $LANGUAGE hello-world
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## Specification
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Write a `Hello World!` function that can greet someone given their name.
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The function should return the appropriate greeting.
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For an input of "Alice", the response should be "Hello, Alice!".
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If a name is not given, the response should be "Hello, World!"
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## Test-Driven Development
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As programmers mature, they eventually want to test their code.
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Here at Exercism we simulate [Test-Driven Development](http://en.wikipedia.org/wiki/Test-driven_development) (TDD), where you write your tests before writing any functionality. The simulation comes in the form of a pre-written test suite, which will signal that you have solved the problem.
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It will also provide you with a safety net to explore other solutions without breaking the functionality.
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### A typical TDD workflow on Exercism:
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1. Run the test file and pick one test that's failing.
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2. Write some code to fix the test you picked.
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3. Re-run the tests to confirm the test is now passing.
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4. Repeat from step 1.
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5. Submit your solution (`exercism submit /path/to/file`)
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## Instructions
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Submissions are encouraged to be general, within reason. Having said that, it's also important not to over-engineer a solution.
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It's important to remember that the goal is to make code as expressive and readable as we can. However, solutions to the hello-world exercise will not be reviewed by a person, but by rikki- the robot, who will offer an encouraging word.
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## Getting Started
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Make sure you have read [D page](http://exercism.io/languages/dlang) on
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exercism.io. This covers the basic information on setting up the development
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environment expected by the exercises.
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## Passing the Tests
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Get the first test compiling, linking and passing by following the [three
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rules of test-driven development](http://butunclebob.com/ArticleS.UncleBob.TheThreeRulesOfTdd).
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Create just enough structure by declaring namespaces, functions, classes,
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etc., to satisfy any compiler errors and get the test to fail. Then write
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just enough code to get the test to pass. Once you've done that,
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uncomment the next test by moving the following line past the next test.
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```D
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static if (all_tests_enabled)
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```
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This may result in compile errors as new constructs may be invoked that
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you haven't yet declared or defined. Again, fix the compile errors minimally
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to get a failing test, then change the code minimally to pass the test,
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refactor your implementation for readability and expressiveness and then
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go on to the next test.
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Try to use standard D facilities in preference to writing your own
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low-level algorithms or facilities by hand. [DRefLanguage](https://dlang.org/spec/spec.html)
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and [DReference](https://dlang.org/phobos/index.html) are references to the D language and D standard library.
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## Source
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This is an exercise to introduce users to using Exercism [http://en.wikipedia.org/wiki/%22Hello,_world!%22_program](http://en.wikipedia.org/wiki/%22Hello,_world!%22_program)
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## Submitting Incomplete Problems
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It's possible to submit an incomplete solution so you can see how others have completed the exercise.
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