[Git][ghc/ghc][master] Type syntax in expressions (#24159, #24572, #24226)

[Marge Bot (@marge-bot)]

Marge Bot pushed to branch master at Glasgow Haskell Compiler / GHC


Commits:
8b2f70a2 by Andrei Borzenkov at 2024-08-01T23:00:46-04:00
Type syntax in expressions (#24159, #24572, #24226)

This patch extends the grammar of expressions with syntax that is
typically found only in types:
  * function types (a -> b), (a ->. b), (a %m -> b)
  * constrained types (ctx => t)
  * forall-quantification (forall tvs. t)

The new forms are guarded behind the RequiredTypeArguments extension,
as specified in GHC Proposal #281. Examples:

  {-# LANGUAGE RequiredTypeArguments #-}
  e1 = f (Int    -> String)          -- function type
  e2 = f (Int %1 -> String)          -- linear function type
  e3 = f (forall a. Bounded a => a)  -- forall type, constraint

The GHC AST and the TH AST have been extended as follows:

   syntax        | HsExpr   | TH.Exp
  ---------------+----------+--------------
   a -> b        | HsFunArr | ConE (->)
   a %m -> b     | HsFunArr | ConE FUN
   ctx => t      | HsQual   | ConstrainedE
   forall a. t   | HsForAll | ForallE
   forall a -> t | HsForAll | ForallVisE

Additionally, a new warning flag -Wview-pattern-signatures has been
introduced to aid with migration to the new precedence of (e -> p :: t).

Co-authored-by: Vladislav Zavialov <vlad.z.4096 at gmail.com>

- - - - -


30 changed files:

- compiler/GHC/Builtin/Names/TH.hs
- compiler/GHC/Driver/Flags.hs
- compiler/GHC/Driver/Session.hs
- compiler/GHC/Hs/Expr.hs
- compiler/GHC/Hs/Instances.hs
- compiler/GHC/Hs/Pat.hs
- compiler/GHC/Hs/Syn/Type.hs
- compiler/GHC/Hs/Type.hs
- compiler/GHC/HsToCore/Expr.hs
- compiler/GHC/HsToCore/Quote.hs
- compiler/GHC/HsToCore/Ticks.hs
- compiler/GHC/Iface/Ext/Ast.hs
- compiler/GHC/Parser.y
- compiler/GHC/Parser/Annotation.hs
- compiler/GHC/Parser/Errors/Ppr.hs
- compiler/GHC/Parser/Errors/Types.hs
- compiler/GHC/Parser/Lexer.x
- compiler/GHC/Parser/PostProcess.hs
- compiler/GHC/Rename/Expr.hs
- compiler/GHC/Rename/HsType.hs
- compiler/GHC/Tc/Errors/Ppr.hs
- compiler/GHC/Tc/Errors/Types.hs
- compiler/GHC/Tc/Gen/App.hs
- compiler/GHC/Tc/Gen/Expr.hs
- compiler/GHC/Tc/Types/Origin.hs
- compiler/GHC/Tc/Zonk/Type.hs
- compiler/GHC/ThToHs.hs
- compiler/GHC/Types/Error/Codes.hs
- compiler/GHC/Types/Hint.hs
- compiler/GHC/Types/Hint/Ppr.hs


The diff was not included because it is too large.


View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/8b2f70a202ec0913515bf4945de789e959ff8cac

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View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/8b2f70a202ec0913515bf4945de789e959ff8cac
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