42 lines
2.0 KiB
Markdown
42 lines
2.0 KiB
Markdown
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# Hints
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## General
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- Read about the `Enum` module in the [official Getting Started guide][getting-started-enum] or on [elixirschool.com][elixir-school-enum].
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- Take a look in the documentation for the full [list of functions in the `Enum` module][enum-functions].
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## 1. Sort items by price
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- There is a [built-in function][enum-sort-by] for sorting enumerables using a sorter function.
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## 2. Find all items with missing prices
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- There is a [built-in function][enum-filter] for filtering enumerables.
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## 3. Update item names
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- There is a [built-in function][enum-map] for transforming every element in an enumerable.
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- There is a [built-in function][string-replace] that can replace all instances of one string with a different one.
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## 4. Increment the item's quantity
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- Maps implement the enumerable protocol.
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- `Enum` functions convert maps to a list of `{key, value}` tuples.
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- There are two different functions that can transform a list of `{key, value}` tuples back into a map using a transformation function. [One of them always returns a new map][map-new], while [the other lets you choose a collectible][enum-into].
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## 5. Calculate the item's total quantity
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- Maps implement the enumerable protocol.
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- `Enum` functions convert maps to a list of `{key, value}` tuples.
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- There is a [built-in function][enum-reduce] for reducing an enumerable to a single value.
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[getting-started-enum]: https://elixir-lang.org/getting-started/enumerables-and-streams.html#enumerables
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[elixir-school-enum]: https://elixirschool.com/en/lessons/basics/enum/
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[enum-functions]: https://hexdocs.pm/elixir/Enum.html#functions
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[enum-sort-by]: https://hexdocs.pm/elixir/Enum.html#sort_by/3
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[enum-filter]: https://hexdocs.pm/elixir/Enum.html#filter/2
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[enum-map]: https://hexdocs.pm/elixir/Enum.html#map/2
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[enum-into]: https://hexdocs.pm/elixir/Enum.html#into/3
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[enum-reduce]: https://hexdocs.pm/elixir/Enum.html#reduce/3
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[map-new]: https://hexdocs.pm/elixir/Map.html#new/2
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[string-replace]: https://hexdocs.pm/elixir/String.html#replace/4
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