use netstrings for framing binary data with json at the end

use netstrings for framing binary data with json at the end

This will be easy to implement with servant. It's also very efficient,
and fairly future-proof. Eg, could add another frame with other data.

This does make it a bit harder to use this protocol, but netstrings
probably take about 5 minutes to implement? Let's see...

import Text.Read
import Data.List

toNetString :: String -> String
toNetString s = show (length s) ++ ":" ++ s ++ ","

nextNetString :: String -> Maybe (String, String)
nextNetString s = case break (== ':') s of
        ([], _) -> Nothing
        (sn, rest) -> do
                n <- readMaybe sn
                let (v, rest') = splitAt n (drop 1 rest)
                return (v, drop 1 rest')

Ok, well, that took about 10 minutes ;-)