Danil Negrienko f324155864 | ||
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.exercism | ||
lib | ||
test | ||
.formatter.exs | ||
.gitignore | ||
HELP.md | ||
HINTS.md | ||
README.md | ||
mix.exs |
README.md
Basketball Website
Welcome to Basketball Website 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
Access Behaviour
Elixir uses code Behaviours to provide common generic interfaces while facilitating specific implementations for each module which implements it. One such common example is the Access Behaviour.
The Access Behaviour provides a common interface for retrieving data from a key-based data structure. The Access Behaviour is implemented for maps and keyword lists, but let's look at its use for maps to get a feel for it. Access Behaviour specifies that when you have a map, you may follow it with square brackets and then use the key to retrieve the value associated with that key.
# Suppose we have these two maps defined (note the difference in the key type)
my_map = %{key: "my value"}
your_map = %{"key" => "your value"}
# Obtain the value using the Access Behaviour
my_map[:key] == "my value"
your_map[:key] == nil
your_map["key"] == "your value"
If the key does not exist in the data structure, then nil
is returned. This can be a source of unintended behavior, because it does not raise an error. Note that nil
itself implements the Access Behaviour and always returns nil
for any key.
Instructions
You are working with a web development team to maintain a website for a local basketball team. The web development team is less familiar with Elixir and is asking for a function to be able to extract data from a series of nested maps to facilitate rapid development.
1. Extract data from a nested map structure
Implement the extract_from_path/2
function to take two arguments:
data
: a nested map structure with data about the basketball team.path
: a string consisting of period-delimited keys to obtain the value associated with the last key.
If the value or the key does not exist at any point in the path, nil
should be returned
data = %{
"team_mascot" => %{
"animal" => "bear",
"actor" => %{
"first_name" => "Noel"
}
}
}
BasketballWebsite.extract_from_path(data, "team_mascot.animal")
# => "bear"
BasketballWebsite.extract_from_path(data, "team_mascot.colors")
# => nil
Use the Access Behaviour when implementing this function.
Do not use any Map
or Kernel
module functions for working with the nested map data structure.
2. Refactor using included functions
Your coworker reviewing your code tells you about a Kernel
module function which does something very similar to your implementation.
Implement get_in_path/2
to use this Kernel
module function.
The arguments expected are the same as part 1.
BasketballWebsite.get_in_path(data, "team_mascot.actor.first_name")
# => "Noel"
Source
Created by
- @neenjaw
Contributed to by
- @angelikatyborska
- @NobbZ