[ghc-steering-committee] Proposal: Type Fixity (#65), Recommendation: Reject

Tue Aug 29 00:30:28 UTC 2017

IMHO, it is a bug that you can provide different fixities in different modules and we should fix that bug.

Manuel

> Richard Eisenberg <rae at cs.brynmawr.edu>:
> 
> Unsurprisingly, I'm in favor of this proposal and do not wish to reject.
> 
> To me, the wart on the language is that we can use the same string for a term-level name and a potentially unrelated type-level name. Of course, this has served many people well, but it does create a certain awkwardness in places (and confusion for beginners!). As long as we have the possibility of one string representing two potentially unrelated names, it seems to be a weakness in expressiveness not to be able to assign different fixities to the names. (And indeed we *can* assign different fixities, as long as we do so in different modules.)
> 
> On the other hand, I am sensitive about all those other raw fish that need frying...
> 
> Richard
> 
>> On Aug 28, 2017, at 5:05 AM, Simon Peyton Jones <simonpj at microsoft.com <mailto:simonpj at microsoft.com>> wrote:
>> 
>> I don't have a strong opinion either way. The strongly reason in favour is encapsulated in Richard's comment
>> https://github.com/ghc-proposals/ghc-proposals/pull/65#issuecomment-319054892 <https://github.com/ghc-proposals/ghc-proposals/pull/65#issuecomment-319054892>
>> which points out that the two T's are entirely unrelated.
>>  
>> I had not fully realised this, but in fact it is /already/ possible to have different fixities for a single lexeme T; a concrete example is here
>> https://github.com/ghc-proposals/ghc-proposals/pull/65#issuecomment-325294776 <https://github.com/ghc-proposals/ghc-proposals/pull/65#issuecomment-325294776>
>>  
>> I added another comment
>> https://github.com/ghc-proposals/ghc-proposals/pull/65#issuecomment-325301080 <https://github.com/ghc-proposals/ghc-proposals/pull/65#issuecomment-325301080>
>> that tries to separate the AST issue from the source-code issue.  I do think we should make the internal change; but I’m unconvinced it’s worth the faff to solve the source-level issue.
>>  
>> Simon
>>  
>>  
>> |  -----Original Message-----
>> |  From: ghc-steering-committee [mailto:ghc-steering-committee-
>> |  bounces at haskell.org <mailto:bounces at haskell.org>] On Behalf Of Joachim Breitner
>> |  Sent: 27 August 2017 19:16
>> |  To: ghc-steering-committee at haskell.org <mailto:ghc-steering-committee at haskell.org>
>> |  Subject: [ghc-steering-committee] Proposal: Type Fixity (#65),
>> |  Recommendation: Reject
>> |  
>> |  Dear Committee,
>> |  
>> |  Ryan Scott’s proposal to allow fixity declaration to explicitly target
>> |  values or types has been brought before us:
>> |  https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com% <https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2FRyanGlScott%2Fghc-proposals%2Fblob%2Ftype-infix%2F0000-type-infix.rst&data=02%7C01%7Csimonpj%40microsoft.com%7Cf83d705bf55c4f02639b08d4ed77cb5e%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636394546146778107&sdata=xa8HXiRK3uYOjGun7UUL3sKDVFvBVTFnXewe15pBGds%3D&reserved=0>
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>> |  
>> |  I (the secretary) nominates myself as the shepherd, so I can right away
>> |  continue giving a recommendation.
>> |  
>> |  I propose to reject this proposal. The main reasons are:
>> |   * it is not clear if there is a real use case for this. Has anyone
>> |     ever complained about the status quo?
>> |     The proposal does not motivate the need for a change well enough.
>> |     (There is a related bug in TH, but that bug can probably simply be
>> |     fixed.)
>> |   * The status quo can be sold as a feature, rather than a short-coming.
>> |     Namely that an operator has a fixed fixity, no matter what namespace
>> |     it lives in.
>> |     This matches morally what other languages do: In Gallina, fixity
>> |     is assigned to names independent of their definition, AFAIK.
>> |   * There is a non-trivial implementation and education overhead, a
>> |     weight that is not pulled by the gains.
>> |  
>> |  If we’d design Haskell from scratch, my verdict might possibly be different
>> |  (but maybe we wouldn’t even allow types and values to share names then…)
>> |  
>> |  
>> |  Please contradict me or indicate consensus by staying silent.
>> |  
>> |  
>> |  Greetings,
>> |  Joachim
>> |  
>> |  --
>> |  Joachim “nomeata” Breitner
>> |    mail at joachim-breitner.de <mailto:mail at joachim-breitner.de>
>> |  
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