00eb17014a
While doing this, I also discovered that there is also a reference to lists in numbers, but that might a bit easier for someone to grasp, given the hint that the koan gives, and the output they see when they run it.
48 lines
1.1 KiB
Elixir
48 lines
1.1 KiB
Elixir
defmodule KeywordLists do
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use Koans
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@intro "KeywordLists"
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koan "Like maps, keyword lists are key-value pairs" do
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kw_list = [foo: "bar"]
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assert kw_list[:foo] == ___
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end
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koan "Keys may be repeated, but only the first is accessed" do
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kw_list = [foo: "bar", foo: "baz"]
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assert kw_list[:foo] == ___
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end
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koan "You could access a second key by removing the first" do
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kw_list = [foo: "bar", foo: "baz"]
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[_|kw_list] = kw_list
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assert kw_list[:foo] == ___
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end
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koan "Keyword lists are just special syntax for lists of two-element tuples" do
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assert [foo: "bar"] == [{___, ___}]
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end
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koan "But unlike maps, the keys in keyword lists must be atoms" do
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not_kw_list = [{"foo", "bar"}]
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assert_raise ArgumentError, fn -> not_kw_list[___] end
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end
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koan "Conveniently keyword lists can be used for function options" do
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transform = fn str, opts ->
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if opts[:upcase] do
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String.upcase(str)
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else
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str
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end
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end
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assert transform.("good", upcase: true) == ___
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assert transform.("good", upcase: false) == ___
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end
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end
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