Fractional precedences? Re: Operator precedence help

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. David, maybe you could help with that from the examples side of things? On Sun, Aug 16, 2020 at 1:27 AM David Feuer wrote:

It sure does seem crowded around there. I'd love to have 4.5 or 5.5. Going up to 6 runs into arithmetic. Going down to 4 hits up against Functor and Applicative stuff, which is a tad unfortunate but I think probably not as bad in practice. So I think I'll go with 4 and 5. Thanks, y'all!

On Sun, Aug 16, 2020, 1:04 AM Henning Thielemann < lemming@henning-thielemann.de> wrote:

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On Sat, 15 Aug 2020, David Feuer wrote:

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Data.Sequence uses the same precedence for both, which strikes me as a bit sad. Surprisingly, I am not seeing other packages on Hackage that define similar operators.

I have the same problem in the 'lapack' bindings.

I like to allow people to write

(row) vector -*# matrix #*# matrix #*| (column) vector

I had no good idea, though, and also chose equal precedence for all operators.

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On Thu, Aug 13, 2020 at 2:50 PM Andreas Abel wrote:

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My hunch would be too look at what the others do to form an opinion.

On 2020-08-13 19:26, David Feuer wrote:

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I'm trying to work out appropriate precedences for operators and

pattern

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synonyms in my brand-new compact-sequences package. I currently have stacks and queues, but I will soon have deques, so let's pretend. For consistency, operators will match pattern synonyms.

(<|), pattern (:<) :: a -> Deque a -> Deque a (|>), pattern (:>) :: Deque a -> a -> Deque a

:< and :> need to have different precedence to allow things like

a :< b :< xs :> c :> d

to work nicely, but what numbers should I pick?

I also have cons and snoc functions. Should I give their backticked spellings fixity declarations? If so, with what precedences?

I would give them the precedence of their infix counterparts.

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