On Thu, Jul 08, 2021 at 06:11:28PM +0800, Kai Ma wrote:
It's proposed here to change the Show instance of String, to achieve the following output:
ghci> print "Hello, 世界” "Hello, 世界”
ghci> print "Hello, мир” "Hello, мир”
ghci> print "Hello, κόσμος” "Hello, κόσμος”
ghci> "Hello, 世界” “Hello, 世界”
ghci> "😀” “😀"
Another possibility is to extend the `Show` class with two new methods and their default implementations: class Show where ... showsPrecUnicode :: Int -> a -> ShowS showsPrecUnicode = showsPrec showListUnicode :: [a] -> ShowS showListUnicode = showList showUnicode :: Show a => a -> String showUnicode x = showsPrecUnicode 0 x "" at which point a small number of classes can override `showUnicode` and `showListUnicode`: instance Show a => Show [a] where showsPrec _ = showList showsPrecUnicode = showListUnicode instance Show Char where showsPrecUnicode = ... -- Unicode char showListUnicode = ... -- Unicode string instance Show Text where showsPrecUnicode = ... -- Unicode text Once these are implemented, "ghci" can be modified to instead used `showUnicode`, rather than `show`, with no new incompatibilities elsewhere. We can also introduce `uprint = putStrLn . showUnicode`, ... This would still require explicit opt-in to use the Unicode show, but it would be available for all `Show` instances, and used by default in "ghci". It would still be a good idea to implement `Render`, which is a related but separate concern. -- Viktor.