23 lines
656 B
Elixir
23 lines
656 B
Elixir
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defmodule Strain do
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@doc """
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Given a `list` of items and a function `fun`, return the list of items where
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`fun` returns true.
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Do not use `Enum.filter`.
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"""
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@spec keep(list :: list(any), fun :: (any -> boolean)) :: list(any)
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def keep([], _fun), do: []
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def keep([head | tail], fun) do
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if fun.(head), do: [head | keep(tail, fun)], else: keep(tail, fun)
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end
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@doc """
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Given a `list` of items and a function `fun`, return the list of items where
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`fun` returns false.
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Do not use `Enum.reject`.
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"""
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@spec discard(list :: list(any), fun :: (any -> boolean)) :: list(any)
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def discard(list, fun), do: keep(list, &!fun.(&1))
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end
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