[Proposal] Renaming (:=:) to (==)

Richard Eisenberg eir at cis.upenn.edu
Sun Sep 29 04:10:46 UTC 2013


-1 from me.

Shachaf stated my argument correctly -- I think that the (:=:) operator means something quite different from the term-level (==) operator, and the name should reflect this. I do like thinking about a better name, though, and I'm happy enough if I'm outvoted here.

Richard

On Sep 28, 2013, at 10:08 PM, Shachaf Ben-Kiki wrote:

> On Sat, Sep 28, 2013 at 6:57 PM, Edward Kmett <ekmett at gmail.com> wrote:
>> As part of the discussion about Typeable, GHC 7.8 is going to include a
>> Data.Type.Equality module that provides a polykinded type equality data
>> type.
>> 
>> I'd like to propose that we rename this type to (==) rather than the (:=:)
>> it was developed under.
>> 
>> We are already using (+), (-), (*), etc. at the type level in type-nats, so
>> it would seem to fit the surrounding convention.
>> 
>> I've done the work of preparing a patch, visible here:
>> 
>> https://github.com/ekmett/packages-base/commit/fb47f8368ad3d40fdd79bdeec334c0554fb17110
>> 
>> Thoughts?
>> 
>> Normally, I'd let this run the usual 2 week course, but we're getting down
>> to the wire for 7.8's release. Once 7.8 ships, we'd basically be stuck with
>> the current name forever.
>> 
>> Discussion Period: 1 week
>> 
>> -Edward Kmett
>> 
> 
> +1. For what it's worth, I suggested that name before, and Richard
> Eisenberg suggested that == should be for type-level Boolean equality:
> <http://markmail.org/message/3yifytgt2k3cfwws>. I'm not convinced,
> though -- this seems fundamental enough to deserve the simplest name
> possible.
> 
> (I'm using that link because the haskell.org mailing list archive
> seems to be gone... Hopefully that comes back, eventually.)
> 
>    Shachaf
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