Add 'traces' function

[sushi-shi]

traceShowId is really useful because you can plug it in anywhere you want without restructuring your code, however, sometimes it outputs too much, or things you use it on do not have Show instance.
So I propose to add a simple traces function:

traces :: Show b => (a -> b) -> a -> a
traces f v = traceShow (f v) v

> fst $ traces fst (5, id)
> 5
> 5

Though it may clash with traces function defined in comonad package. However Control.Comonad.Traced also has trace, so one would need to be careful with this module anyway.

[chshersh]

@sheepfleece Thanks for the proposal! This function sounds useful; I don't mind adding it to relude. I'm not worried that much about the collision with the traces function from the comonad package, I'm more concerned about the collision with variables that have name traces (it's a legit variable name). So let's think more about the name. Maybe a different name that has fewer chances to conflict can be introduced (e.g. traceFun or traceWithShow or traceOn).

[sushi-shi]

@chshersh Thank you! I think traceFun sounds good enough. It may be less elegant then traceOn (and, of course, traces). However, when grepping a subset of Hackage I have locally downloaded it didn't find a single hit, compared to the other two. And traceFun is also easy to remember, in contrast with traceWithShow.

[chshersh]

@sheepfleece We've been thinking and discussing with @vrom911 possible names and consistent naming schemes for trace* functions and decided to stick with traceShowWith. It makes sense, that we have traceShow and traceShowWith adds an extra ability to the existing function (it also consistent with sortWith). PR is welcome 🙂

[elldritch]

Hey @chshersh, any plans on doing a new release any time soon? I've been running into situations in Advent where having this combinator would be really useful.

[chshersh]

@liftM We work on relude in our free time, and our work depends on availability, so we don't have any deadlines or release schedules. But we do have milestones to plan what we want to include in the next release.

Nevertheless, this shouldn't be a blocker for you if you want to use the latest version of relude in your own projects, as you can depend on packages directly from GitHub with either Cabal or Stack.

• Cabal documentation
• Stack example