ryandv

    You must learn to sit perfectly still with every muscle tense for long periods.

    Various things will happen to you while you are practising these positions; they must be carefully analysed and described.

    Note down the duration of practice; the severity of the pain (if any) which accompanies it, the degree of rigidity attained, and any other pertinent matters.

    When you have progressed up to the point that a saucer filled to the brim with water and poised upon the head does not spill one drop during a whole hour,
    and when you can no longer perceive the slightest tremor in any muscle; when, in short, you are perfectly steady and easy, you will be admitted for examination;
    and, should you pass, you will be instructed in more complex and difficult practices.

    -- given a path to a PEM encoded PKCS#8 formatted RSA private key and a
    -- JWT Claims Set (RFC 7519) represented as a strict ByteString,
    -- return a strict ByteString representing a base64 encoded RSA256-signed JWS.
    generateJWT :: FilePath -> B.ByteString -> IO (Maybe B.ByteString)
    generateJWT fp claims = (fmap unJwt <$>) . (maybe (return Nothing) (fmap eitherToMaybe . encodeClaims) =<<)
                                             $ fromPKCS8 fp
      where eitherToMaybe = preview _Right
            encodeClaims  = (flip $ rsaEncode RS256) claims