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| author | Sebastian Graf <sgraf1337@gmail.com> | 2019-11-03 19:42:52 +0000 |
|---|---|---|
| committer | Sebastian Graf <sebastian.graf@kit.edu> | 2021-03-12 11:01:09 +0100 |
| commit | 27abfd0023589cb6ee3363512d160df2d1016275 (patch) | |
| tree | e7a45b9557f6c4086cfe3197875454a6bf654889 /compiler/GHC/Tc/TyCl/Instance.hs | |
| parent | df8e8ba267ffd7b8be0702bd64b8c39532359461 (diff) | |
| download | haskell-wip/unlifted-data.tar.gz | |
Implement the UnliftedDatatypes extensionwip/unlifted-data
GHC Proposal: 0265-unlifted-datatypes.rst
Discussion: https://github.com/ghc-proposals/ghc-proposals/pull/265
Issues: https://gitlab.haskell.org/ghc/ghc/-/issues/19523
Implementation Details: Note [Implementation of UnliftedDatatypes]
This patch introduces the `UnliftedDatatypes` extension. When this extension is
enabled, GHC relaxes the restrictions around what result kinds are allowed in
data declarations. This allows data types for which an unlifted or
levity-polymorphic result kind is inferred.
The most significant changes are in `GHC.Tc.TyCl`, where
`Note [Implementation of UnliftedDatatypes]` describes the details of the
implementation.
Fixes #19523.
Diffstat (limited to 'compiler/GHC/Tc/TyCl/Instance.hs')
| -rw-r--r-- | compiler/GHC/Tc/TyCl/Instance.hs | 15 |
1 files changed, 9 insertions, 6 deletions
diff --git a/compiler/GHC/Tc/TyCl/Instance.hs b/compiler/GHC/Tc/TyCl/Instance.hs index 657e1bffe7..8bfb5370bb 100644 --- a/compiler/GHC/Tc/TyCl/Instance.hs +++ b/compiler/GHC/Tc/TyCl/Instance.hs @@ -727,7 +727,7 @@ tcDataFamInstDecl mb_clsinfo tv_skol_env ; traceTc "tcDataFamInstDecl" $ vcat [ text "Fam tycon:" <+> ppr fam_tc , text "Pats:" <+> ppr pats - , text "visiblities:" <+> ppr (tcbVisibilities fam_tc pats) + , text "visibilities:" <+> ppr (tcbVisibilities fam_tc pats) , text "all_pats:" <+> ppr all_pats , text "ty_binders" <+> ppr ty_binders , text "fam_tc_binders:" <+> ppr (tyConBinders fam_tc) @@ -940,12 +940,15 @@ tcDataFamInstHeader mb_clsinfo fam_tc outer_bndrs fixity fam_name = tyConName fam_tc data_ctxt = DataKindCtxt fam_name - -- See Note [Implementation of UnliftedNewtypes] in GHC.Tc.TyCl, wrinkle (2). + -- See Note [Implementation of UnliftedNewtypes] in GHC.Tc.TyCl, families (2), + -- and Note [Implementation of UnliftedDatatypes]. tc_kind_sig Nothing - = do { unlifted_newtypes <- xoptM LangExt.UnliftedNewtypes - ; if unlifted_newtypes && new_or_data == NewType - then newOpenTypeKind - else pure liftedTypeKind + = do { unlifted_newtypes <- xoptM LangExt.UnliftedNewtypes + ; unlifted_datatypes <- xoptM LangExt.UnliftedDatatypes + ; case new_or_data of + NewType | unlifted_newtypes -> newOpenTypeKind + DataType | unlifted_datatypes -> newOpenTypeKind + _ -> pure liftedTypeKind } -- See Note [Result kind signature for a data family instance] |