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| author | Simon Peyton Jones <simonpj@microsoft.com> | 2015-06-24 22:35:32 +0100 |
|---|---|---|
| committer | Simon Peyton Jones <simonpj@microsoft.com> | 2015-06-26 08:33:04 +0100 |
| commit | ff8a67164b294b5eb6caee38ec59e7e400e025dc (patch) | |
| tree | 66ff5cd8dd34c9c804fcf04dd0612063fde47f9d /compiler/hsSyn/HsUtils.hs | |
| parent | 9195927d093504e233225dfb40f2f6b95a78925e (diff) | |
| download | haskell-ff8a67164b294b5eb6caee38ec59e7e400e025dc.tar.gz | |
Use a Representaional coercion for data families
When we have
data instance T (a,b) = MkT a b
we make a represntation type
data TPair a b = MkT a b
plus an axiom to connect the two
ax a b :: T (a,b) ~R TPair a b
Previously this was a Nominal equality, and that worked ok
but seems illogical since Nominal equalities are between
types that the programmer thinks of as being equal. But
TPair is not visible to the programmer; indeed we call it
the "representation TyCon". So a Representational equality
seems more suitable here.
Diffstat (limited to 'compiler/hsSyn/HsUtils.hs')
| -rw-r--r-- | compiler/hsSyn/HsUtils.hs | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/compiler/hsSyn/HsUtils.hs b/compiler/hsSyn/HsUtils.hs index fd3d5efa6a..2242d10f76 100644 --- a/compiler/hsSyn/HsUtils.hs +++ b/compiler/hsSyn/HsUtils.hs @@ -23,7 +23,7 @@ module HsUtils( mkSimpleMatch, unguardedGRHSs, unguardedRHS, mkMatchGroup, mkMatchGroupName, mkMatch, mkHsLam, mkHsIf, mkHsWrap, mkLHsWrap, mkHsWrapCo, mkHsWrapCoR, mkLHsWrapCo, - coToHsWrapper, mkHsDictLet, mkHsLams, + coToHsWrapper, coToHsWrapperR, mkHsDictLet, mkHsLams, mkHsOpApp, mkHsDo, mkHsComp, mkHsWrapPat, mkHsWrapPatCo, mkLHsPar, mkHsCmdCast, @@ -477,11 +477,11 @@ mkHsWrap :: HsWrapper -> HsExpr id -> HsExpr id mkHsWrap co_fn e | isIdHsWrapper co_fn = e | otherwise = HsWrap co_fn e -mkHsWrapCo :: TcCoercion -- A Nominal coercion a ~N b +mkHsWrapCo :: TcCoercionN -- A Nominal coercion a ~N b -> HsExpr id -> HsExpr id mkHsWrapCo co e = mkHsWrap (coToHsWrapper co) e -mkHsWrapCoR :: TcCoercion -- A Representational coercion a ~R b +mkHsWrapCoR :: TcCoercionR -- A Representational coercion a ~R b -> HsExpr id -> HsExpr id mkHsWrapCoR co e = mkHsWrap (coToHsWrapperR co) e |