Parse PostgreSQL database URL

ParseDatabaseUrl.hs

parseDatabaseUrl :: String -> Maybe ConnectInfo
parseDatabaseUrl s = do
    let (s1, s2) = break (== ':') s
    unless (s1 == "postgres") (fail "Invalid scheme")
    let (s3, s4) = break (\c -> c /= ':' && c /= '/') s2
    unless (s3 == "://") (fail "Invalid separator")
    let (user, s6) = break (== ':') s4
    when (length user < 1) (fail "Invalid user")
    let s7 = drop 1 s6
        (password, s8) = break (== '@') s7
    when (length password < 1) (fail "Invalid password")
    let s9 = drop 1 s8
        (host, s10) = break (== ':') s9
    when (length host < 1) (fail "Invalid host")
    let s11 = drop 1 s10
        (portStr, s12) = break (== '/') s11
    port <- readMaybe portStr
    let database = drop 1 s12
    when (length database < 1) (fail "Invalid database")
    pure $ ConnectInfo host port user password database