Text.Printf replacement?

Twan van Laarhoven twanvl at gmail.com
Fri Sep 6 17:18:55 CEST 2013

On 06/09/13 04:16, Bart Massey wrote:
> A final issue has to do with the return type of Text.Printf.printf,
> which is polymorphic between String and IO a. I'm sure this seemed
> like a good idea at the time, but it's not so ideal today: GHC gives a
> warning when printf is used at IO a unless you explicitly ignore the
> result.

You can probably force the `a` to be `()` by using:

     instance (a ~ ()) => PrintfType (IO a) where ...

But that is of course not standard Haskell.


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