November 2018 - ghc-steering-committee

[Proposal] #175: Lift.liftTyped (recommendation: accept)
by Ben Gamari 02 May '19

02 May '19

Hi everyone, I have been asked to Shepard #175, which proposes to add a `liftTyped` method to the `Lift` typeclass used to lift Haskell values into Template Haskell splices. Currently the `Lift` typeclass provides no guarantee of type-safety, even when used in a Typed Template Haskell context. The proposal resolves this limitation by adding a typed lifting operation to the `Lift` class: class Lift t where lift :: t -> Q Exp liftTyped :: t -> Q (TExp t) While this addition will break manually-written `Lift` instances, we recommended that users derive such instances for quite a while now, so it is not expected that the breakage will be wide-spread. In light of this, I recommend that we accept this proposal. Given that we will likely want to get this in to 8.8, I suggest that we limit the discussion to a week unless there is dissent. Cheers, - Ben

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Bundling patterns with type synonyms (#28)
by Christopher Allen 26 Jan '19

26 Jan '19

The proposal I'm reviewing is: Bundling patterns with type synonyms by Bertram Felgenhauer and Joe Hermaszewski https://github.com/ghc-proposals/ghc-proposals/pull/28 Having reviewed the proposal and gone through some of the GHC Trac history, I think we should accept this proposal. There are a couple of open questions, ambiguities, and potential downsides but the overall complexity of the proposal doesn't cause me great concern. Cheers, Chris Allen

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Please review #175: Lift.liftTyped, Shepherd: Ben Gamari
by Joachim Breitner 05 Nov '18

05 Nov '18

Dear Committee, this is your secretary speaking: Add `liftTyped` to the `Lift` typeclass, by Alec Theriault, was proposed https://github.com/ghc-proposals/ghc-proposals/pull/175 https://github.com/harpocrates/ghc-proposals/blob/lift-typed/proposals/0000… I propose Ben as the shepherd. Please reach consensus as described in https://github.com/ghc-proposals/ghc-proposals#committee-process I suggest you make a recommendation, in a new e-mail thread with the proposal number in the subject, about the decision, maybe point out debatable points, and assume that anyone who stays quiet agrees with you. Thanks, Joachim -- Joachim Breitner mail(a)joachim-breitner.de http://www.joachim-breitner.de/

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Status
by Joachim Breitner 05 Nov '18

05 Nov '18

Dear committee, This was a quiet, but very productive month. Since the last status update, we * were asked to review these proposals: #173 The dot type operator (shepherd: Eric) #174 lower precedence for UNPACK (shepherd: Joachim) #166 List instances in ghci (shepherd: Iavor) #175 liftTyped (shepherd: Ben) * got a recommendation from shepherds about: #170 Unrestricted OverloadedLables (rec: accept) #28 Bundling patterns with type synonyms (rec changed to reject) #174 lower precedence for UNPACK (rec: accept) #173 The dot type operator (rec: accept) #111 Linear types (rec: conditional accept) #166 List instances in ghci (rec: accept) * decided about the following proposals #174 lower precedence for UNPACK (accept) #168 fail with Overloaded Strings (accept) #173 The dot type operator (accept) #170 Unrestricted OverloadedLables (accept) #111 Linear types (rec: conditional accept) #166 List instances in ghci (accept) We currently have to act on the following 6 proposals, 3 less than last round, continuing a pleasant downward trend. liftTyped https://github.com/ghc-proposals/ghc-proposals/pull/175 Shepherd: Ben Status: Waiting for recommendation. Type annotated quoters https://github.com/ghc-proposals/ghc-proposals/pull/125 Shepherd: Manuel Status: Still waiting for recommendation. Manuel? Provenance-Qualified Package Imports https://github.com/ghc-proposals/ghc-proposals/pull/115 Shepherd: Ben Status: Still waiting for recommendation. This is pretty old! ExtraCommas https://github.com/ghc-proposals/ghc-proposals/pull/87 Shepherd: Chris Recommendation: accept Status: Met with some reservation. Chris, what is the status of discussion? Or-Patterns https://github.com/ghc-proposals/ghc-proposals/pull/43 Shepherd: Manuel Recommendation: accept Status: Round 2 discussion ebbed down. Manuel? Bundling patterns with synonyms https://github.com/ghc-proposals/ghc-proposals/pull/28 Shepherd: Chris Recommendation: reject Status: Rejection imminent Cheers, Joachim -- Joachim Breitner mail(a)joachim-breitner.de http://www.joachim-breitner.de/

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Discussion: List instances for a type in GHCi #166
by Iavor Diatchki 05 Nov '18

05 Nov '18

Hello, I'd like to start the discussion about feature request #166, "List instances for a type in GHCi". In short, the idea is that we add a new command to GHCi, `:instances TYPE`, which given a type, will show the list of instances---for any class---that could be used with this type. It seems like this could be a potentially handy thing to do, and it doesn't really interfere with anything else, so I recommend that we accept it. Please let me know what you think. -Iavor

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Proposal #170: Unrestricted OverloadedLabels (was: Uppercase OverloadedLabels), rec: accept
by Vitaly Bragilevsky 05 Nov '18

05 Nov '18

Hi all, The proposal #170: Unrestricted OverloadedLabels (was: Uppercase OverloadedLabels) (https://github.com/ghc-proposals/ghc-proposals/pull/170) was updated to allow any nonempty alphanumeric string following a # under OverloadedLabels. So I repeat my recommendation to accept it. Please speak up within a week if you have any concerns. Silence is understood as agreement. Regards, Vitaly

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Proposal #173: The dot type operator, rec: accept
by Eric Seidel 05 Nov '18

05 Nov '18

Hello, This proposal would extend the parser to allow the '.' character to appear in type operators, allowing one to write code like the following: ``` type (f . g) x = f (g x) foo :: (Maybe . Either Int) Bool foo = Just (Right True) ``` I recommend we accept the proposal, as it would resolve an odd inconsistency between the term and type languages. The main downside seems to be that combining a type-level '.' with a 'forall' is a bit hard to read, but I think the benefits of a more consistent syntax outweigh this concern. Eric

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