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| author | Andrew Martin <andrew.thaddeus@gmail.com> | 2019-05-12 09:23:25 -0400 |
|---|---|---|
| committer | Marge Bot <ben+marge-bot@smart-cactus.org> | 2019-06-14 10:48:13 -0400 |
| commit | effdd948056923f3bc03688c24d7e0339d6272f5 (patch) | |
| tree | 02a3cb68ce1680db89c8440ba8beea808cbf4a11 /compiler/hsSyn | |
| parent | 3bc6df3223f62a8366e2e4267bac23aa08e6a939 (diff) | |
| download | haskell-effdd948056923f3bc03688c24d7e0339d6272f5.tar.gz | |
Implement the -XUnliftedNewtypes extension.
GHC Proposal: 0013-unlifted-newtypes.rst
Discussion: https://github.com/ghc-proposals/ghc-proposals/pull/98
Issues: #15219, #1311, #13595, #15883
Implementation Details:
Note [Implementation of UnliftedNewtypes]
Note [Unifying data family kinds]
Note [Compulsory newtype unfolding]
This patch introduces the -XUnliftedNewtypes extension. When this
extension is enabled, GHC drops the restriction that the field in
a newtype must be of kind (TYPE 'LiftedRep). This allows types
like Int# and ByteArray# to be used in a newtype. Additionally,
coerce is made levity-polymorphic so that it can be used with
newtypes over unlifted types.
The bulk of the changes are in TcTyClsDecls.hs. With -XUnliftedNewtypes,
getInitialKind is more liberal, introducing a unification variable to
return the kind (TYPE r0) rather than just returning (TYPE 'LiftedRep).
When kind-checking a data constructor with kcConDecl, we attempt to
unify the kind of a newtype with the kind of its field's type. When
typechecking a data declaration with tcTyClDecl, we again perform a
unification. See the implementation note for more on this.
Co-authored-by: Richard Eisenberg <rae@richarde.dev>
Diffstat (limited to 'compiler/hsSyn')
| -rw-r--r-- | compiler/hsSyn/HsTypes.hs | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/compiler/hsSyn/HsTypes.hs b/compiler/hsSyn/HsTypes.hs index b186b36abb..130e39efab 100644 --- a/compiler/hsSyn/HsTypes.hs +++ b/compiler/hsSyn/HsTypes.hs @@ -62,6 +62,7 @@ module HsTypes ( mkHsOpTy, mkHsAppTy, mkHsAppTys, mkHsAppKindTy, ignoreParens, hsSigType, hsSigWcType, hsLTyVarBndrToType, hsLTyVarBndrsToTypes, + hsConDetailsArgs, -- Printing pprHsType, pprHsForAll, pprHsForAllExtra, pprHsExplicitForAll, @@ -912,6 +913,14 @@ instance (Outputable arg, Outputable rec) ppr (RecCon rec) = text "RecCon:" <+> ppr rec ppr (InfixCon l r) = text "InfixCon:" <+> ppr [l, r] +hsConDetailsArgs :: + HsConDetails (LHsType a) (Located [LConDeclField a]) + -> [LHsType a] +hsConDetailsArgs details = case details of + InfixCon a b -> [a,b] + PrefixCon xs -> xs + RecCon r -> map (cd_fld_type . unLoc) (unLoc r) + {- Note [ConDeclField passs] ~~~~~~~~~~~~~~~~~~~~~~~~~ |