#11529: Show instance of Char should print literals for non-ascii printable charcters -------------------------------------+------------------------------------- Reporter: nushio | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.3 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Show instance for non-ascii characters prints their character codes. This is sad for Haskell users that speaks language other than English. {{{#!hs
'A' 'A' 'Ä' '\196' '漢' '\28450' print $ [(++"'s dad"), (++"'s mom")] <*> ["Simon", "John"] ["Simon's dad","John's dad","Simon's mom","John's mom"] print $ [(++"の父"), (++"の母")] <*> ["田中", "山田"] ["\30000\20013\12398\29238","\23665\30000\12398\29238","\30000\20013\12398\27597","\23665\30000\12398\27597"] }}}
The function that needs improvement is showLitChar in GHC.Show, which currently prints any character larger than ASCII code 127 by its character code: http://haddock.stackage.org/lts-5.1/base-4.8.2.0/src/GHC-Show.html {{{#!hs showLitChar :: Char -> ShowS showLitChar c s | c > '\DEL' = showChar '\\' (protectEsc isDec (shows (ord c)) s) }}} On the other hand, there is GHC.Unicode.isPrint, the predicate for printable Unicode characters, that is calling on a foreign function u_iswprint for the knowledge. https://hackage.haskell.org/package/base-4.8.2.0/docs/src/GHC.Unicode.html#i... I think one of the solution is to import and call u_iswprint from GHC.Show, too, but I don't know it's against any design choices. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11529 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler