Generalized Pickler

Since string constants are delimited by double quotes, we need to escape embedded double quotes. We do this using the backslash character. But that means we also need to escape embedded occurrences of the backslash

fun {Escape S}
   case S
   of nil then nil
   [] &\\|S then &\\|&\\|{Escape S}
   [] &" |S then &\\|&" |{Escape S}
   []   H|S then       H|{Escape S}
   end
end