Hi everyone,
I believe there is broad consensus to accept this proposal. One point of
detail that has arisen on the proposal thread
(https://github.com/ghc-proposals/ghc-proposals/pull/493#issuecomment-1831697143)
is whether to deprecate and remove the awkward and undocumented
multi-type form
{-# SPECIALISE f :: Int -> Int
, Bool -> Bool
, Float -> Float #-}
since users can equally well write the clearer
{-# SPECIALISE f :: Int -> Int #-}
{-# SPECIALISE f :: Bool -> Bool #-}
{-# SPECIALISE f :: Float -> Float #-}
The current text of the proposal retains the multi-type form, but
discussion on the proposal thread suggests deprecating it instead,
subject to the usual requirement that if/when this is implemented, GHC
will issue a warning and continue to accept the old syntax for at least
3 releases before completely removing it.
I suggest we accept the proposal on the basis that it will be amended to
deprecate the multi-type form. If you disagree, please object in the
next week or so.
Cheers,
Adam
On 19/12/2023 03:02, Eric Seidel wrote:
> Apologies, this sounds like an obvious win. +1
>
> On Mon, Dec 18, 2023, at 04:36, Simon Peyton Jones wrote:
>> Eric, Joachim, Chris
>>
>> You have not yet responded (I think) to Adam's recommendation. RSVP!
>>
>> https://docs.google.com/spreadsheets/d/1e6GdwHmAjeDEUhTvP-b18MDkpTfH3SMHhFu5F3nDIWc/edit?usp=sharing
>>
>> Simon
>>
>> On Wed, 29 Nov 2023 at 08:25, Adam Gundry <adam@well-typed.com> wrote:
>>> Dear all,
>>>
>>> Richard and Simon propose to generalise SPECIALISE pragmas to allow
>>> expressions, not just type signatures:
>>>
>>> https://github.com/ghc-proposals/ghc-proposals/pull/493
>>> https://github.com/goldfirere/ghc-proposals/blob/specialise/proposals/0000-specialise-expressions.rst
>>>
>>> This does not add anything fundamentally new, because such SPECIALISE
>>> pragmas can be translated using the existing RULES machinery, but it
>>> does make several idioms substantially more convenient:
>>>
>>> * Using type applications in a SPECIALISE pragma to avoid repetition
>>>
>>> * Manual call-pattern specialisation
>>>
>>> * Loop unrolling
>>>
>>> Thus I propose we accept this proposal.
>>>
>>> Cheers,
>>>
>>> Adam
--
Adam Gundry, Haskell Consultant
Well-Typed LLP, https://www.well-typed.com/
Registered in England & Wales, OC335890
27 Old Gloucester Street, London WC1N 3AX, England
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