Prettier 1.10.2
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--arrow-parens always

Input:

const sha256 = (data) => crypto.createHash("sha256").update(data).digest("hex");

Output:

const sha256 = (data) =>
  crypto
    .createHash("sha256")
    .update(data)
    .digest("hex");

Expected behavior:

The input was perfectly fine as it stood; it was a nice one-liner, exactly 80 characters long. Breaking it into multiple lines just makes it less clear. Is there a specific reason prettier behaves this way?