[core libraries] Re: Add taggedTrace to Debug.Trace

[Edward Kmett]

What different users would do with such a prefix, how to display it, etc. varies just enough that i’m somewhat hesitant to grow the API. I’m a very weak -1. But I’d happily let anybody else on the committee override that if they had a strong preference.

-Edward

> On Jun 7, 2018, at 5:40 PM, Ben Gamari <ben at smart-cactus.org> wrote:
> 
> Yuji Yamamoto <whosekiteneverfly at gmail.com> writes:
> 
>> Nice to meet you, GHC Developers!
>> I'm new to contributing to GHC.
>> 
> Hi Yuji!
> 
> Thanks for your proposal.
> 
> I think this is likely best handled by the Core Libraries Committee
> (CC'd). Let's see what they say.
> 
> 
> 
>> Today let me suggest new APIs of the Debug.Trace
>> <http://hackage.haskell.org/package/base-4.11.1.0/docs/Debug-Trace.html>
>> module, named:
>> 
>>   - taggedTraceShowId :: Show a => String -> a -> a
>>   - taggedTraceWith :: (a -> String) -> String -> a -> a
>> 
>> These are inspired by Elm's Debug.log
>> <http://package.elm-lang.org/packages/elm-lang/core/5.1.1/Debug#log>
>> function.
>> The prefix "tagged" is named after its argument
>> <https://github.com/elm-lang/core/blob/5.1.1/src/Native/Debug.js#L5>.
>> 
>> I mean, these new APIs prepend a string as a tag to the output by
>> traceShowId etc.
>> It helps us recognize what the printed values stand for.
>> I frequently want such functions and write them manually or copy-and-paste
>> from the Debug.TraceUtils.
>> I'm tired of that. That's why I made this suggestion.
>> 
>> *Comparison with the existing solution*
>> 
>>   - Debug.TraceUtils
>>   <http://hackage.haskell.org/package/TraceUtils-0.1.0.2/docs/Debug-TraceUtils.html>
>>   :
>>      - Essentially, this suggestion is to add APIs already implemented by
>>      TraceUtils.
>>      - As the document of TraceUtils suggests, we can copy and paste the
>>      functions from its source, but it's still tiresome.
>>   - Combine Debug.Trace.traceShowId with Debug.Trace.trace:
>>      - e.g. trace "Tag" $ traceShowId x
>>      - A bit hard to type.
>>      - trace always prints a newline, which makes it difficult to tell the
>>      tags from the printed value.
>> 
>> After receiving some feedback here, I'm going to submit to
>> https://github.com/ghc-proposals/ghc-proposals
>> Thanks in advance!
>> 
> 
> Personally, I do like the "With" variant as I regularly find myself
> needing things like this. I'm a bit unsure of whether we want to bake
> the "tag" notion into the interface, however.
> 
> Cheers,
> 
> - Ben
> 
> -- 
> You received this message because you are subscribed to the Google Groups "haskell-core-libraries" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to haskell-core-libraries+unsubscribe at googlegroups.com.
> For more options, visit https://groups.google.com/d/optout.