如何在Elixir/Erlang中实现高效的to_ascii函数

您将如何在Elixir或Erlang中实现高效的to_ascii函数

扫描字符串的每个字符并调用string.printable？看起来是个很糟糕的选择

  def to_ascii(s) do
    case String.printable?(s) do
      true -> s
      false -> _to_ascii(String.codepoints(s), "")
    end
  end

  defp _to_ascii([], acc), do: acc
  defp _to_ascii([c | rest], acc) when ?c in 32..127, do: _to_ascii(rest, acc <> c)
  defp _to_ascii([_ | rest], acc), do: _to_ascii(rest, acc)

例如：

s_in = <<"hello", 150, " ", 180, "world", 160>>
s_out = "hello world" # valid ascii only i.e 32 .. 127

使用理解：

你好，你好！ 对于使用理解：

你好，你好！ 对于Erlang中的

1> Bin = <<"hello привет ¡hola!"/utf8>>.
<<104,101,108,108,111,32,208,191,209,128,208,184,208,178,
  208,181,209,130,32,194,161,104,111,108,97,33>>
2> << <<C>> || <<C>> <= Bin, C >= 32, C =< 127 >>. 
<<"hello  hola!">>
3> [ C || <<C>> <= Bin, C >= 32, C =< 127 ].      
"hello  hola!"

在二郎

1> Bin = <<"hello привет ¡hola!"/utf8>>.
<<104,101,108,108,111,32,208,191,209,128,208,184,208,178,
  208,181,209,130,32,194,161,104,111,108,97,33>>
2> << <<C>> || <<C>> <= Bin, C >= 32, C =< 127 >>. 
<<"hello  hola!">>
3> [ C || <<C>> <= Bin, C >= 32, C =< 127 ].      
"hello  hola!"

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显然不是我；责怪何塞：显然不是我；责怪何塞：