43 lines
1018 B
Elixir
43 lines
1018 B
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 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: String.upcase(str)
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end
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assert transform.("good", upcase: true) == ___
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end
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end
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