diff options
Diffstat (limited to 'compiler/GHC/Core/Coercion/Axiom.hs')
| -rw-r--r-- | compiler/GHC/Core/Coercion/Axiom.hs | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/compiler/GHC/Core/Coercion/Axiom.hs b/compiler/GHC/Core/Coercion/Axiom.hs index 4ecbb6cc3d..7046273ae5 100644 --- a/compiler/GHC/Core/Coercion/Axiom.hs +++ b/compiler/GHC/Core/Coercion/Axiom.hs @@ -184,9 +184,10 @@ Note [Storing compatibility] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ During axiom application, we need to be aware of which branches are compatible with which others. The full explanation is in Note [Compatibility] in -FamInstEnv. (The code is placed there to avoid a dependency from CoAxiom on -the unification algorithm.) Although we could theoretically compute -compatibility on the fly, this is silly, so we store it in a CoAxiom. +GHc.Core.FamInstEnv. (The code is placed there to avoid a dependency from +GHC.Core.Coercion.Axiom on the unification algorithm.) Although we could +theoretically compute compatibility on the fly, this is silly, so we store it +in a CoAxiom. Specifically, each branch refers to all other branches with which it is incompatible. This list might well be empty, and it will always be for the @@ -233,8 +234,8 @@ data CoAxBranch { cab_loc :: SrcSpan -- Location of the defining equation -- See Note [CoAxiom locations] , cab_tvs :: [TyVar] -- Bound type variables; not necessarily fresh - , cab_eta_tvs :: [TyVar] -- Eta-reduced tyvars -- See Note [CoAxBranch type variables] + , cab_eta_tvs :: [TyVar] -- Eta-reduced tyvars -- cab_tvs and cab_lhs may be eta-reduced; see -- Note [Eta reduction for data families] , cab_cvs :: [CoVar] -- Bound coercion variables |