[Haskell-cafe] Can we improve Show instance for non-ascii charcters?

[Gershom B]

Backwards compatibility is important, but not an absolute. I’d be curious if anyone can point to instances where software might _rely_ on the show instance for strings not displaying unicode characters?

—Gershom


On February 3, 2016 at 5:03:58 PM, David Feuer (david.feuer at gmail.com) wrote:
> There's one open now. thomie commented (
> https://ghc.haskell.org/trac/ghc/ticket/11529#comment:4 ) that it's
> possible to hook up your choice of showing function as the one GHCi should
> use to display values. This strikes me as the best available approach
> preserving backwards compatibility. Adding a GHCi flag for this might be
> reasonable.
>  
> On Wed, Feb 3, 2016 at 4:11 PM, Atze van der Ploeg wrote:
>  
> > I think we can all agree these characters should be shown. Maybe a GHC bug
> > report is a good idea?
> > On 02/03/2016 10:37 AM, Takayuki Muranushi wrote:
> > > 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.
> >
> > +1 for only escaping non-printable characters.
> >
> > > Yesterday, I had a chance to teach Haskell (in Japanese,) and I had to
> > > use English in some of the most exciting examples, like the
> > > Applicative List example above. I would heartedly like to see GHC
> > > improve in these directions, so that we can make more happy learning
> > > materials on Haskell.
> >
> > As a workaround, perhaps you can avoid using print/show with core data
> > structures. Using your applicative example:
> >
> > > mapM_ putStrLn $ [(++"の父"), (++"の母")] <*> ["田中", "山田"]
> > 田中の父
> > 山田の父
> > 田中の母
> > 山田の母
> >
> > For other data structures, you can write your own Show instance:
> >
> > data Name = Name String String
> >
> > instance Show Name where
> > show (Name family given) = family ++ given
> >
> > > print $ Person "山田" "太郎"
> > 山田太郎
> >
> > Travis
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