[RFC] Support Unicode characters in instance Show String

Viktor Dukhovni ietf-dane at dukhovni.org
Fri Jul 9 17:05:37 UTC 2021


On Fri, Jul 09, 2021 at 08:04:40AM +0900, Travis Cardwell via Libraries wrote:
> On Fri, Jul 9, 2021 at 3:18 AM H├ęcate wrote:
> > I guess this is the perfect time to come up with a Render typeclass that
> > targets end-users rather than satisfying 'read . show = id'.
> 
> This is the primary motivation of the TTC (Textual Type Classes)
> library: <https://hackage.haskell.org/package/ttc>.
> 
> It provides a Render type class that is analogous to Show and a Parse
> type class that is analogous to Read.  No instances are declared so that
> users of the library can implement instances as required for each
> application, but default instances for core types are available.

One promising feature of this is that the target type is not restricted
to just `String`, but rather `Render` produces a `Textual` value, which
can be a String, Text, ByteString, or a Text or Binary `builder`.  I
would prefer to also see a ByteString `Builder` as an option, but the
high level design feels sound.

-- 
    Viktor.


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