133 lines
4.5 KiB
Markdown
133 lines
4.5 KiB
Markdown
# Wine Cellar
|
|
|
|
Welcome to Wine Cellar on Exercism's Elixir Track.
|
|
If you need help running the tests or submitting your code, check out `HELP.md`.
|
|
If you get stuck on the exercise, check out `HINTS.md`, but try and solve it without using those first :)
|
|
|
|
## Introduction
|
|
|
|
## Keyword Lists
|
|
|
|
Keyword lists are a key-value data structure.
|
|
|
|
```elixir
|
|
[month: "April", year: 2018]
|
|
```
|
|
|
|
Keyword lists are lists of `{key, value}` [tuples][exercism-tuples], and can also be written as such, but the shorter syntax is more widely used.
|
|
|
|
```elixir
|
|
[month: "April"] == [{:month, "April"}]
|
|
# => true
|
|
```
|
|
|
|
Keys in a keyword list must be [atoms][exercism-atoms], but the values can be anything. Each key can be used more than once. The key-value pairs in a keyword list are ordered.
|
|
|
|
You can work with keyword lists using the same approaches as for lists, or you can use the `Keyword` module.
|
|
|
|
[exercism-tuples]: https://exercism.org/tracks/elixir/concepts/tuples
|
|
[exercism-atoms]: https://exercism.org/tracks/elixir/concepts/atoms
|
|
|
|
## Instructions
|
|
|
|
You are the manager of a fancy restaurant that has a sizable wine cellar. A lot of your customers are demanding wine enthusiasts. Finding the right bottle of wine for a particular customer is not an easy task.
|
|
|
|
As a tech-savvy restaurant owner, you decided to speed up the wine selection process by writing an app that will let guests filter your wines by their preferences.
|
|
|
|
## 1. Explain wine colors
|
|
|
|
On the welcome screen of your app, you want to display a short explanation of each wine color.
|
|
|
|
Implement the `WineCellar.explain_colors/0` function. It takes no arguments and returns a keyword list with wine colors as keys and explanations as values.
|
|
|
|
| Color | Explanation |
|
|
| -------- | -------------------------------------------------------------------------- |
|
|
| `:white` | Fermented without skin contact. |
|
|
| `:red` | Fermented with skin contact using dark-colored grapes. |
|
|
| `:rose` | Fermented with some skin contact, but not enough to qualify as a red wine. |
|
|
|
|
## 2. Get all wines of a given color
|
|
|
|
A bottle of wine is represented as a 3-tuple of grape variety, year, and country of origin. The wines are stored by wine color in a keyword list.
|
|
|
|
```elixir
|
|
[
|
|
white: {"Chardonnay", 2015, "Italy"},
|
|
white: {"Pinot grigio", 2017, "Germany"},
|
|
red: {"Pinot noir", 2016, "France"},
|
|
rose: {"Dornfelder", 2018, "Germany"}
|
|
]
|
|
```
|
|
|
|
Implement the `WineCellar.filter/3` function. It should take a keyword list of wines, a color atom and a keyword list of options, with a default value of `[]`. The function should return a list of wines of a given color.
|
|
|
|
```elixir
|
|
WineCellar.filter(
|
|
[
|
|
white: {"Chardonnay", 2015, "Italy"},
|
|
white: {"Pinot grigio", 2017, "Germany"},
|
|
red: {"Pinot noir", 2016, "France"},
|
|
rose: {"Dornfelder", 2018, "Germany"}
|
|
],
|
|
:white
|
|
)
|
|
# => [
|
|
# {"Chardonnay", 2015, "Italy"},
|
|
# {"Pinot grigio", 2017, "Germany"}
|
|
# ]
|
|
```
|
|
|
|
## 3. Get all wines of a given color bottled in a given year
|
|
|
|
Extend the `WineCellar.filter/3` function. When given a `:year` option, the function should return a list of wines of a given color from a given year.
|
|
|
|
Use the already-implemented `WineCellar.filter_by_year/2` function. It takes a list of wines and a year as arguments and returns a list of wines from a given year.
|
|
|
|
```elixir
|
|
WineCellar.filter(
|
|
[
|
|
white: {"Chardonnay", 2015, "Italy"},
|
|
white: {"Pinot grigio", 2017, "Germany"},
|
|
red: {"Pinot noir", 2016, "France"},
|
|
rose: {"Dornfelder", 2018, "Germany"}
|
|
],
|
|
:white,
|
|
year: 2015
|
|
)
|
|
# => [
|
|
# {"Chardonnay", 2015, "Italy"}
|
|
# ]
|
|
```
|
|
|
|
## 4. Get all wines of a given color bottled in a given country
|
|
|
|
Extend the `WineCellar.filter/3` function. When given a `:country` option, the function should return a list of wines of a given color from a given country.
|
|
|
|
Use the already-implemented `WineCellar.filter_by_country/2` function. It takes a list of wines and a country as arguments and returns a list of wines from a given country.
|
|
|
|
Make sure that the function works when given both the `:year` and the `:country` option, in any order.
|
|
|
|
```elixir
|
|
WineCellar.filter(
|
|
[
|
|
white: {"Chardonnay", 2015, "Italy"},
|
|
white: {"Pinot grigio", 2017, "Germany"},
|
|
red: {"Pinot noir", 2016, "France"},
|
|
rose: {"Dornfelder", 2018, "Germany"}
|
|
],
|
|
:white,
|
|
year: 2015,
|
|
country: "Germany"
|
|
)
|
|
# => []
|
|
```
|
|
|
|
## Source
|
|
|
|
### Created by
|
|
|
|
- @angelikatyborska
|
|
|
|
### Contributed to by
|
|
|
|
- @neenjaw |