Hello Mark, On 2015-01-31 at 07:18:53 +0100, Mark Lentczner wrote: [...]
The value of generalizing the list functions greatly over estimated: There have been alternate, more generalized Preludes for ages... and I don't see much use of them. Sure, they require some futzing with imports to use - but that isn't that high of a bar, and yet clearly their value rarely merits it in people's minds.
* alternative (even more) generalised preludes exist * there isn't much use of them * the inconvenience of using them outweights their benefit ----------------- -> the value of generalising list functions is greatly over-estimated If I get your argument right (please correct me if I got it wrong), I'm not convinced the argument to be valid. IMHO it's rather a chicken-and-egg problem, that nobody wants to waste time basing their project on some shaky experimental alternative prelude which replaces `base` with no guarantee of future support/stability. And the less users an alternative prelude has, the less there's incentive to keep it supported/maintained. Also, if it's an experimental/research prelude, chances are it's still evolving and changing in incompatible ways. Another reason not to trust your project with it. Finally, I'd rather interpret the argument to mean that alternative preludes fail as a means to provide any meaningful feedback for design-choices due to lack of use by a representable sample of users. Otoh, the FTP-changes were continuously tested against packages on Hackage to get empirical feedback on their impact, and if needed tweak the design to have the most compatibility while achieving the goal of making Foldable/Traversable more of a first-class citizen[1]. That's probably more due diligence than any other alternative generalising preludes can produce.
Maybe I don't write the most clever code (code golf excepted), but I rarely pine for a more generalized length. Or for all to work over Foldable... etc. For the few times when I need something like Foldable I don't see what the issue is with importing qualified and using prefixes. People here seem to feel that a "F." is somehow an ugly wart on their code... but that is just the way it is with most software: You need a lot of things in scope, you use namespaces of one sort or another.
[...] [1]: IMO, we either endorse the Traversable/Foldable abstraction as a recommended abstraction for Haskell code by making it a properly integrated first-class citizen (and integrating it in a future Haskell Report), or we deprecate it (and eventually remove it from `base` altogether, as what's its right to exist there otherwise?). The current situation in `base` doesn't give a clear picture about whether Foldable/Traversable is recommended or rather an historic artifact, IMO. Cheers, hvr