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

David Feuer david.feuer at gmail.com
Wed Feb 3 22:03:51 UTC 2016


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 <atzeus at gmail.com> 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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