Fractional precedences? Re: Operator precedence help
John Cotton Ericson
John.Ericson at Obsidian.Systems
Wed Sep 2 22:29:36 UTC 2020
I definitely prefer this approach. I do not like absolutely levels,
whether natural numbers or fractional. At the end of the day, that's all
order-maintance for a *global* total preorder, and such a design will
always result in unforeseeable interactions between
independently-developed operators, not to mention increasingly
This may sound like low-priority design pedantry, but I suspect
(probably because I myself was taught with scheme) that
spooky-action-at-a-distance precedence greatly harms beginning
programmers, causing confusion or at least delaying the understanding
that expressions are arbitrarily deep trees.
On 8/17/20 12:12 PM, Carter Schonwald wrote:
> Oh yeah!
> I feel like everyone’s wondered about that approach. But it definitely
> would need some experiments to validate. But in some ways it’d be
> super fascinating.
> On Mon, Aug 17, 2020 at 9:40 AM Henning Thielemann
> <lemming at henning-thielemann.de <mailto:lemming at henning-thielemann.de>>
> On Sun, 16 Aug 2020, Carter Schonwald wrote:
> > I do think that the work needed to actually support fractional
> > precedence in ghc is pretty minimal. Or at least I remember
> having a
> > conversation about it a few years ago, and the conclusion was that
> > adding precedence would be super easy to do, but just lacked
> any good
> > motivating example from real libraries.
> I remember this discussion, too, and I guess that it was started
> by Simon
> Marlow and it ended with recalling that decades ago something more
> advanced was discussed: Groups of equal precedence and relations
> the groups. But that one was too complicated to be implemented.
> Libraries mailing list
> Libraries at haskell.org
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