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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/typecheck/TcGenGenerics.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/typecheck/TcGenGenerics.hs')
| -rw-r--r-- | compiler/typecheck/TcGenGenerics.hs | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/compiler/typecheck/TcGenGenerics.hs b/compiler/typecheck/TcGenGenerics.hs index 649aa5fc99..63fee7fc28 100644 --- a/compiler/typecheck/TcGenGenerics.hs +++ b/compiler/typecheck/TcGenGenerics.hs @@ -506,7 +506,7 @@ tc_mkRepFamInsts gk tycon metaDts mod = in newGlobalBinder mod (mkGen (nameOccName (tyConName tycon))) (nameSrcSpan (tyConName tycon)) - ; let axiom = mkSingleCoAxiom rep_name tyvars fam_tc appT repTy + ; let axiom = mkSingleCoAxiom Nominal rep_name tyvars fam_tc appT repTy ; newFamInst SynFamilyInst axiom } -------------------------------------------------------------------------------- |