Does anybody with their elbows in the code think variable interpolation and/or multi-line strings are good/doable ideas? Would this be the sort of change one could make without a lot of previous familiarity with the implementation of Hugs/Ghc?

I don't think it is really necessary to add the feature to the language, since you can program something very similar for yourself in user-code. Here's a sample of a single-character macro expansion within strings, that took a couple of minutes to write. module Printf where import Maybe(fromMaybe) hereDocument :: (Show a, Show b) => a -> b -> String hereDocument v w = "Multi-line string starts here\ \ and uses string gap delimiters.\n\ \ Variable names like $$a are filled in from the\n\ \ bindings specified in the `with` clause,\n\ \ e.g. $$a = $a, $$b = $b\n\ \ and unused bindings pass through e.g. $$c = $c." `with` [('a',show v), ('b',show w)] with :: String -> [(Char,String)] -> String [] `with` env = [] ('$':'$':cs) `with` env = '$': cs `with` env ('$':c:cs) `with` env = s ++ cs `with` env where s = fromMaybe ('$':c:[]) (lookup c env) (c:cs) `with` env = c : cs `with` env Regards, Malcolm