36 lines
2.5 KiB
Markdown
36 lines
2.5 KiB
Markdown
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# Hints
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## General
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- Read about [charlists][getting-started-charlists], [Unicode and code points][getting-started-code-points], and [`case`][getting-started-case] in the official Getting Started guide.
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- Read about [charlists][elixirschool-charlists] and [`case`][elixirschool-case] on elixirschool.com.
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## 1. Sanitize existing usernames by removing everything but lowercase letters
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- Use recursion to iterate over a charlist.
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- There is a [built-in function][kernel-case] that allows us to compare a given value against many patterns.
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- There is a [special syntax][syntax-reference-code-points] for getting a character's code point. It can be used in guards.
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- Charlists are lists of code points, and code points, being numbers, can be [compared][kernel-greater-than] to one another.
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- Lowercase Latin letters all have [consecutive code points][unicode-character-reference], in alphabetical order.
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- There is [a built-in function][kernel-concat-list] that allows you to concatenate two lists.
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## 2. Allow underscores
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- There is a [special syntax][syntax-reference-code-points] for getting a character's code point. It can be used in guards and it works for punctuation characters too.
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- There is [a built-in function][kernel-concat-list] that allows you to concatenate two lists.
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## 3. Substitute German characters
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- There is a [special syntax][syntax-reference-code-points] for getting a character's code point. It can be used in guards and it works for non-Latin letters too.
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- There is [a built-in function][kernel-concat-list] that allows you to concatenate two lists.
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[syntax-reference-code-points]: https://hexdocs.pm/elixir/syntax-reference.html#integers-in-other-bases-and-unicode-code-points
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[getting-started-code-points]: https://elixir-lang.org/getting-started/binaries-strings-and-char-lists.html#unicode-and-code-points
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[getting-started-charlists]: https://elixir-lang.org/getting-started/binaries-strings-and-char-lists.html#charlists
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[getting-started-case]: https://elixir-lang.org/getting-started/case-cond-and-if.html#case
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[elixirschool-charlists]: https://elixirschool.com/en/lessons/basics/strings/#charlists
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[elixirschool-case]: https://elixirschool.com/en/lessons/basics/control-structures/#case
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[unicode-character-reference]: https://en.wikibooks.org/wiki/Unicode/Character_reference/0000-0FFF
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[kernel-concat-list]: https://hexdocs.pm/elixir/Kernel.html#++/2
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[kernel-greater-than]: https://hexdocs.pm/elixir/Kernel.html#%3E/2
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[kernel-case]: https://hexdocs.pm/elixir/Kernel.SpecialForms.html#case/2
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