∀ (c : Char),
  String.utf8EncodeCharFast c =
    if c.val ≤ 127 then [c.val.toUInt8]
    else
      if c.val ≤ 2047 then [(c.val >>> 6).toUInt8 &&& 31 ||| 192, c.val.toUInt8 &&& 63 ||| 128]
      else
        if c.val ≤ 65535 then
          [(c.val >>> 12).toUInt8 &&& 15 ||| 224, (c.val >>> 6).toUInt8 &&& 63 ||| 128, c.val.toUInt8 &&& 63 ||| 128]
        else
          [(c.val >>> 18).toUInt8 &&& 7 ||| 240, (c.val >>> 12).toUInt8 &&& 63 ||| 128,
            (c.val >>> 6).toUInt8 &&& 63 ||| 128, c.val.toUInt8 &&& 63 ||| 128]