053: Show Char においてエスケープ未対応

instance Show Char where
  -- todo: escape
  show c = ['\'', c, '\'']
  showList cs = (:) '"' . showl cs
    where -- showl "" = (:) '"'
          showl [] = (:) '"'
          -- showl ('"':cs) = (++) "\\\"" . showl cs
          showl (c:cs) = showLitChar c . showl cs

-- todo: should convert to printable characters
showLitChar c = (++) [c]