[ghc-steering-committee] #380 GHC2021: Third status update

[Alejandro Serrano Mena]

 Dear all,
I would like to raise a few points with respect to some extensions:
- What should we do with those which are superseded? I voted ‘yes’ to
NullaryTypeClasses because it’s implied by MultiParamTypeClasses [
https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/glasgow_exts.html#extension-NullaryTypeClasses].
I don’t think we’ll end up in a situation in which the former is accepted
but not the latter, but it’s worth mentioning.
- ‘MonadFailDesugaring’ is enabled by default since 8.6.1 [
https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/glasgow_exts.html#extension-MonadFailDesugaring].
We could keep the status quo, and say that the extension is not part of
GHC2021, but it’s enabled by default in GHC; but that seems like a weird
outcome to me.

Regards,
Alejandro

On 7 Dec 2020 at 19:17:17, Joachim Breitner <mail at joachim-breitner.de>
wrote:

> Dear Committe,
>
> it’s been two weeks since we started voting. We are still short one
> vote (Cale, release the suspsense!). But also, there are still plenty
> of “maybes” in your vote. I encourage you to change them to yes or no
> (at least for those extensions that are near the edge), so that we have
> more clarity on which extensions are actually worth spending emails on.
>
> As always, the table
>
> https://github.com/ghc-proposals/ghc-proposals/blob/ghc2021/proposals/0000-ghc2021.rst#data
> has the current data. (And even even got community contributions to
> improve its readability. Yay!)
>
> We discussed many extensions on (and I might have missed some):
>
> * The innnocence of PostfixOperators was pointed out, and widely
>   appreciated
> * Joachim pleads for UnicodeSyntax
> * InstanceSigs worries seems to have been addressed, it’s on its way
>   in
> * Whether OverloadedString is harmless enough.
> * Whether ViewPatterns are good enough (given that alternative ideas
>   exist)
> * That ForeignFunctionInterfaces is actually part of Haskell2010
> * That this isn’t quite the right time to ditch StarIsType
> * CUSKs vs. StandaloneKindSignatures
> * BlockArguments is liked by some, but may be too new
> * GADTs were advocated for a lot, but also a bit against, so not
>   uncontroversial
> * Same with ExistentialQuantification
> * PolyKinds were advocated for (and got many votes)
> * ScopedTypeVariables is wanted on by default by some,
>   despite the fact that nobody believes it’s the last
>   word on that design corner. Alejandro argues that it’s
>   ok to include it even if it will change in GHC202X again,
>   but elsewhere SPJ says that GHC2021 should only include extensions
>   we have reason to hope are stable and stay around .
> * Arnaud wonders about the hesitation to include
>   FunctionalDependencies
>
>
> Applying the actual quota of ⅔ out of 11, i.e. 8 votes, these would go
> in no matter how Cale votes:
>
>   BangPatterns, BinaryLiterals, ConstrainedClassMethods,
>   ConstraintKinds, DeriveDataTypeable, DeriveFoldable, DeriveFunctor,
>   DeriveGeneric, DeriveLift, DeriveTraversable, EmptyCase,
>   EmptyDataDecls, EmptyDataDeriving, ExplicitForAll, FlexibleContexts,
>   FlexibleInstances, GADTSyntax, GeneralisedNewtypeDeriving,
>   HexFloatLiterals, ImportQualifiedPost, InstanceSigs, KindSignatures,
>   MultiParamTypeClasses, NamedFieldPuns, NumericUnderscores,
>   PolyKinds, PostfixOperators, RankNTypes, StandaloneDeriving,
>   StarIsType, TypeApplications, TypeOperators, TypeSynonymInstances
>
> The following have 7 votes, which is the quorum based on 10 ballots:
>
>   ExistentialQuantification, ForeignFunctionInterface, MonoLocalBinds,
>   NegativeLiterals, RecordWildCards, StandaloneKindSignatures,
>   TypeFamilies
>
> And these are one vote short:
>
>   DataKinds, DerivingStrategies, GADTs, NamedWildCards,
>   ScopedTypeVariables, TupleSections, UnicodeSyntax, ViewPatterns
>
>
> Not sure how useful the list of symmetric difference report is, but
> here it is:
>
> alejandro
> would miss:
> DataKinds, DerivingStrategies, FunctionalDependencies, GADTs,
> LambdaCase, MonadFailDesugaring, NamedWildCards,
> NoMonomorphismRestriction, NullaryTypeClasses, NumDecimals,
> OverloadedLists, OverloadedStrings, ScopedTypeVariables, TupleSections,
> UnicodeSyntax, ViewPatterns
> doesn’t want:
> none!
>
> arnaud
> would miss:
> Arrows, DerivingStrategies, ExplicitNamespaces, FunctionalDependencies,
> GADTs, MonadFailDesugaring, PartialTypeSignatures,
> TypeFamilyDependencies, ViewPatterns
> doesn’t want:
> ExistentialQuantification, ImportQualifiedPost, InstanceSigs,
> NamedFieldPuns, PolyKinds, RankNTypes, RecordWildCards,
> StandaloneKindSignatures, TypeSynonymInstances
>
> eric
> would miss:
> DataKinds, DefaultSignatures, DisambiguateRecordFields,
> ExplicitNamespaces, FunctionalDependencies, GADTs, MonadFailDesugaring,
> NamedWildCards, OverloadedLists, OverloadedStrings,
> PartialTypeSignatures, PatternSynonyms, RoleAnnotations,
> ScopedTypeVariables, TypeFamilyDependencies
> doesn’t want:
> EmptyDataDeriving, ForeignFunctionInterface
>
> iavor
> would miss:
> BlockArguments, CApiFFI, MultiWayIf, NoMonomorphismRestriction,
> NullaryTypeClasses, ParallelListComp, RecursiveDo, UnicodeSyntax,
> UnliftedNewtypes
> doesn’t want:
> ConstrainedClassMethods, EmptyCase, ExplicitForAll, GADTSyntax,
> GeneralisedNewtypeDeriving, InstanceSigs, KindSignatures,
> MonoLocalBinds, NegativeLiterals, PolyKinds, StandaloneKindSignatures,
> StarIsType, TypeApplications, TypeFamilies, TypeOperators
>
> joachim
> would miss:
> DataKinds, DerivingStrategies, DerivingVia, LambdaCase, NamedWildCards,
> NondecreasingIndentation, RoleAnnotations, TupleSections,
> UnicodeSyntax, UnliftedFFITypes, UnliftedNewtypes
> doesn’t want:
> ConstrainedClassMethods, ExistentialQuantification,
> TypeSynonymInstances
>
> richard
> would miss:
> BlockArguments, DefaultSignatures, DerivingStrategies, DerivingVia,
> DisambiguateRecordFields, ExplicitNamespaces, LexicalNegation,
> NamedWildCards, NumDecimals, ParallelListComp, RoleAnnotations,
> TemplateHaskellQuotes, TupleSections, UnicodeSyntax, UnliftedNewtypes,
> ViewPatterns
> doesn’t want:
> MonoLocalBinds, NegativeLiterals, RecordWildCards, TypeFamilies
>
> simonm
> would miss:
> DataKinds, DefaultSignatures, GADTs, LambdaCase, LiberalTypeSynonyms,
> MultiWayIf, NoMonomorphismRestriction, NondecreasingIndentation,
> NumDecimals, OverloadedStrings, PatternSynonyms, ScopedTypeVariables,
> TupleSections, UnicodeSyntax
> doesn’t want:
> DeriveLift, NumericUnderscores, TypeApplications, TypeOperators
>
> spj
> would miss:
> NoMonomorphismRestriction, NullaryTypeClasses, OverloadedLists,
> OverloadedStrings, ParallelListComp, RecursiveDo, RoleAnnotations,
> ScopedTypeVariables, ViewPatterns
> doesn’t want:
> ForeignFunctionInterface, GeneralisedNewtypeDeriving, NegativeLiterals,
> RecordWildCards, TypeFamilies
>
> tom
> would miss:
> BlockArguments, DataKinds, DefaultSignatures, DerivingStrategies,
> DerivingVia, DisambiguateRecordFields, DuplicateRecordFields,
> ExplicitNamespaces, FunctionalDependencies, GADTs, LambdaCase,
> LexicalNegation, LiberalTypeSynonyms, MagicHash, MultiWayIf,
> NamedWildCards, NullaryTypeClasses, NumDecimals, PackageImports,
> ParallelListComp, QuasiQuotes, RoleAnnotations, ScopedTypeVariables,
> TemplateHaskell, TemplateHaskellQuotes, TupleSections,
> TypeFamilyDependencies, UnboxedSums, UnboxedTuples, UnicodeSyntax,
> UnliftedNewtypes, ViewPatterns
> doesn’t want:
> ForeignFunctionInterface, MonoLocalBinds, StarIsType
>
> vitaly
> would miss:
> DataKinds, DerivingStrategies, DerivingVia, GADTs, LambdaCase,
> MonadFailDesugaring, NamedWildCards, OverloadedLists,
> OverloadedStrings, ScopedTypeVariables, TupleSections, ViewPatterns
> doesn’t want:
> ExistentialQuantification, StandaloneKindSignatures
>
> Cheers,
> Joachim
>
> --
> Joachim Breitner
>  mail at joachim-breitner.de
>  http://www.joachim-breitner.de/
>
>
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