Re: [Haskell-beginners] How to use Text.Printf w/ custom types

PrintfArg does not have toUPrint. The functions in there are formatArg and parseFormat. PrintfType is according to its documentation, an interface that you shall not implement yourself. Baa schrieb am Fr., 24. Nov. 2017 um 15:08 Uhr:

I talked about PrintfType and its method `hspr`.

With PrintfArgs the same problem:

instance PrintfArg JobEvent where toUPrintf _ = UString "aaa"

^^^ toUPrintf is not visible ERROR here...

Header of this file looks like:

module Text.Printf( printf, hPrintf, PrintfType, HPrintfType, PrintfArg, IsChar ) where

so methods are not exported? And I don't see any Internal subpackage... OK, no problem, I switched already to very cool `formatting` library :)

Thanks a lot!

...

It appears PrintfArg and its methods are fully exported.

On Fri, Nov 24, 2017 at 8:19 AM, Baa wrote:

...

But how to do it if "methods" are not exporting?

...

According to https://hackage.haskell.org/package/base-4.10.0.0/docs/ Text-Printf.html#g:2, you only need to implement `PrintfArg`. There is also an example for `()`.

Baa schrieb am Fr., 24. Nov. 2017 um 13:33 Uhr:

...

Hello All!

As I understand to use Text.Printf.printf with custom types or to return result as Text instead of String I must implement some class instances: PrintfType, PrintfArg. But how to do this if they are exported from module as type-names only - without its methods (i.e. not "Printf (..)", but "Printf") ?

I tried to import Text.Printf.Internal but seems that no such submodule...

Any ideas?

=== Best regards, Paul _______________________________________________ Beginners mailing list Beginners@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners

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