diff options
Diffstat (limited to 'compiler/GHC/Tc/Types/Constraint.hs')
| -rw-r--r-- | compiler/GHC/Tc/Types/Constraint.hs | 20 |
1 files changed, 10 insertions, 10 deletions
diff --git a/compiler/GHC/Tc/Types/Constraint.hs b/compiler/GHC/Tc/Types/Constraint.hs index 05fd70c674..3950f1db77 100644 --- a/compiler/GHC/Tc/Types/Constraint.hs +++ b/compiler/GHC/Tc/Types/Constraint.hs @@ -117,8 +117,8 @@ import qualified Data.Semigroup ( (<>) ) Note [CEqCan occurs check] ~~~~~~~~~~~~~~~~~~~~~~~~~~ A CEqCan relates a CanEqLHS (a type variable or type family applications) on -its left to an arbitrary type on its right. It is used for rewriting, in the -flattener. Because it is used for rewriting, it would be disastrous if the RHS +its left to an arbitrary type on its right. It is used for rewriting. +Because it is used for rewriting, it would be disastrous if the RHS were to mention the LHS: this would cause a loop in rewriting. We thus perform an occurs-check. There is, of course, some subtlety: @@ -146,8 +146,8 @@ The occurs check is performed in GHC.Tc.Utils.Unify.checkTypeEq. -} -- | A 'Xi'-type is one that has been fully rewritten with respect --- to the inert set; that is, it has been flattened by the algorithm --- in GHC.Tc.Solver.Flatten. (Historical note: 'Xi', for years and years, +-- to the inert set; that is, it has been rewritten by the algorithm +-- in GHC.Tc.Solver.Rewrite. (Historical note: 'Xi', for years and years, -- meant that a type was type-family-free. It does *not* mean this -- any more.) type Xi = TcType @@ -257,7 +257,7 @@ data Hole , hole_loc :: CtLoc -- ^ Where hole was written } -- For the hole_loc, we usually only want the TcLclEnv stored within. - -- Except when we flatten, where we need a whole location. And this + -- Except when we rewrite, where we need a whole location. And this -- might get reported to the user if reducing type families in a -- hole type loops. @@ -298,7 +298,7 @@ data CtIrredStatus | BlockedCIS HoleSet -- this constraint is blocked on the coercion hole(s) listed -- See Note [Equalities with incompatible kinds] in GHC.Tc.Solver.Canonical - -- Wrinkle (4a). Why store the HoleSet? See Wrinkle (2a) of that + -- Wrinkle (4a). Why store the HoleSet? See Wrinkle (2) of that -- same Note. -- INVARIANT: A BlockedCIS is a homogeneous equality whose -- left hand side can fit in a CanEqLHS. @@ -527,19 +527,19 @@ tyCoFVsOfCts = foldr (unionFV . tyCoFVsOfCt) emptyFV -- | Returns free variables of WantedConstraints as a non-deterministic -- set. See Note [Deterministic FV] in "GHC.Utils.FV". tyCoVarsOfWC :: WantedConstraints -> TyCoVarSet --- Only called on *zonked* things, hence no need to worry about flatten-skolems +-- Only called on *zonked* things tyCoVarsOfWC = fvVarSet . tyCoFVsOfWC -- | Returns free variables of WantedConstraints as a deterministically -- ordered list. See Note [Deterministic FV] in "GHC.Utils.FV". tyCoVarsOfWCList :: WantedConstraints -> [TyCoVar] --- Only called on *zonked* things, hence no need to worry about flatten-skolems +-- Only called on *zonked* things tyCoVarsOfWCList = fvVarList . tyCoFVsOfWC -- | Returns free variables of WantedConstraints as a composable FV -- computation. See Note [Deterministic FV] in "GHC.Utils.FV". tyCoFVsOfWC :: WantedConstraints -> FV --- Only called on *zonked* things, hence no need to worry about flatten-skolems +-- Only called on *zonked* things tyCoFVsOfWC (WC { wc_simple = simple, wc_impl = implic, wc_holes = holes }) = tyCoFVsOfCts simple `unionFV` tyCoFVsOfBag tyCoFVsOfImplic implic `unionFV` @@ -548,7 +548,7 @@ tyCoFVsOfWC (WC { wc_simple = simple, wc_impl = implic, wc_holes = holes }) -- | Returns free variables of Implication as a composable FV computation. -- See Note [Deterministic FV] in "GHC.Utils.FV". tyCoFVsOfImplic :: Implication -> FV --- Only called on *zonked* things, hence no need to worry about flatten-skolems +-- Only called on *zonked* things tyCoFVsOfImplic (Implic { ic_skols = skols , ic_given = givens , ic_wanted = wanted }) |