Support TH constructs added in GHC 9.4 #169
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We desugar `PromotedInfixT` to applications of `DConT` to two arguments, mirroring the existing treatment for `InfixT`. By a similar token, attempting to desugar `PromotedUInfixT` results in an error, just like what would happen if you attempt to desugar `UInfixT` today. Addresses one part of #157.
Template Haskell support for `default` declarations was added in GHC 9.4. Addresses one part of #157.
The `OPAQUE` pragma was introduced in GHC 9.4. Addresses one part of #157.
We desugar `\cases` expressions to ordinary lambda expressions, much like `\case` expressions are currently desguared. Addresses one part of #157.
goldfirere
requested changes
Jun 6, 2022
Our treatment of promoted data constructors (in the forms of `PromotedT` and `PromotedInfixT`) is somewhat unusual, but there are practical reasons for doing so. The new `Note [Desugaring promoted types]` explains what these reasons are.
goldfirere
approved these changes
Jun 7, 2022
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This adds support for the following TH constructs, newly introduced in GHC 9.4:
PromotedInfixTandPromotedUInfixT. These are desugared very similarly toInfixTandUInfixT.DefaultD(defaultdeclarations).OpaqueP(OPAQUEpragmas).LamCasesE(\casesexpressions). These are desugared to ordinary lambda expressions, similarly to howLamCaseEis desugared.For more details, refer to the individual commit messages.
This addresses four check boxes in #157.