Safe Haskell | None |
---|---|
Language | Haskell2010 |
Coercion
Contents
Description
Module for (a) type kinds and (b) type coercions,
as used in System FC. See Expr
for
more on System FC and how coercions fit into it.
Synopsis
- data Coercion
- type CoercionN = Coercion
- type CoercionR = Coercion
- type CoercionP = Coercion
- data UnivCoProvenance
- data CoercionHole
- data LeftOrRight
- data Var
- type CoVar = Id
- type TyCoVar = Id
- data Role
- ltRole :: Role -> Role -> Bool
- coVarTypes :: CoVar -> Pair Type
- coVarKind :: CoVar -> Type
- coVarKindsTypesRole :: CoVar -> (Kind, Kind, Type, Type, Role)
- coVarRole :: CoVar -> Role
- coercionType :: Coercion -> Type
- coercionKind :: Coercion -> Pair Type
- coercionKinds :: [Coercion] -> Pair [Type]
- mkCoercionType :: Role -> Type -> Type -> Type
- coercionRole :: Coercion -> Role
- coercionKindRole :: Coercion -> (Pair Type, Role)
- mkReflCo :: Role -> Type -> Coercion
- mkRepReflCo :: Type -> Coercion
- mkNomReflCo :: Type -> Coercion
- mkCoVarCo :: CoVar -> Coercion
- mkCoVarCos :: [CoVar] -> [Coercion]
- mkAxInstCo :: Role -> CoAxiom br -> BranchIndex -> [Type] -> [Coercion] -> Coercion
- mkUnbranchedAxInstCo :: Role -> CoAxiom Unbranched -> [Type] -> [Coercion] -> Coercion
- mkAxInstRHS :: CoAxiom br -> BranchIndex -> [Type] -> [Coercion] -> Type
- mkUnbranchedAxInstRHS :: CoAxiom Unbranched -> [Type] -> [Coercion] -> Type
- mkAxInstLHS :: CoAxiom br -> BranchIndex -> [Type] -> [Coercion] -> Type
- mkUnbranchedAxInstLHS :: CoAxiom Unbranched -> [Type] -> [Coercion] -> Type
- mkPiCo :: Role -> Var -> Coercion -> Coercion
- mkPiCos :: Role -> [Var] -> Coercion -> Coercion
- mkCoCast :: Coercion -> Coercion -> Coercion
- mkSymCo :: Coercion -> Coercion
- mkTransCo :: Coercion -> Coercion -> Coercion
- mkTransAppCo :: Role -> Coercion -> Type -> Type -> Role -> Coercion -> Type -> Type -> Role -> Coercion
- mkNthCo :: Int -> Coercion -> Coercion
- mkNthCoRole :: Role -> Int -> Coercion -> Coercion
- mkLRCo :: LeftOrRight -> Coercion -> Coercion
- mkInstCo :: Coercion -> Coercion -> Coercion
- mkAppCo :: Coercion -> Coercion -> Coercion
- mkAppCos :: Coercion -> [Coercion] -> Coercion
- mkTyConAppCo :: HasDebugCallStack => Role -> TyCon -> [Coercion] -> Coercion
- mkFunCo :: Role -> Coercion -> Coercion -> Coercion
- mkFunCos :: Role -> [Coercion] -> Coercion -> Coercion
- mkForAllCo :: TyVar -> Coercion -> Coercion -> Coercion
- mkForAllCos :: [(TyVar, Coercion)] -> Coercion -> Coercion
- mkHomoForAllCos :: [TyVar] -> Coercion -> Coercion
- mkHomoForAllCos_NoRefl :: [TyVar] -> Coercion -> Coercion
- mkPhantomCo :: Coercion -> Type -> Type -> Coercion
- mkHomoPhantomCo :: Type -> Type -> Coercion
- toPhantomCo :: Coercion -> Coercion
- mkUnsafeCo :: Role -> Type -> Type -> Coercion
- mkHoleCo :: CoercionHole -> Role -> Type -> Type -> Coercion
- mkUnivCo :: UnivCoProvenance -> Role -> Type -> Type -> Coercion
- mkSubCo :: Coercion -> Coercion
- mkAxiomInstCo :: CoAxiom Branched -> BranchIndex -> [Coercion] -> Coercion
- mkProofIrrelCo :: Role -> Coercion -> Coercion -> Coercion -> Coercion
- downgradeRole :: Role -> Role -> Coercion -> Coercion
- maybeSubCo :: EqRel -> Coercion -> Coercion
- mkAxiomRuleCo :: CoAxiomRule -> [Coercion] -> Coercion
- mkCoherenceCo :: Coercion -> Coercion -> Coercion
- mkCoherenceRightCo :: Coercion -> Coercion -> Coercion
- mkCoherenceLeftCo :: Coercion -> Coercion -> Coercion
- mkKindCo :: Coercion -> Coercion
- castCoercionKind :: Coercion -> Coercion -> Coercion -> Coercion
- mkHeteroCoercionType :: Role -> Kind -> Kind -> Type -> Type -> Type
- instNewTyCon_maybe :: TyCon -> [Type] -> Maybe (Type, Coercion)
- type NormaliseStepper ev = RecTcChecker -> TyCon -> [Type] -> NormaliseStepResult ev
- data NormaliseStepResult ev
- = NS_Done
- | NS_Abort
- | NS_Step RecTcChecker Type ev
- composeSteppers :: NormaliseStepper ev -> NormaliseStepper ev -> NormaliseStepper ev
- mapStepResult :: (ev1 -> ev2) -> NormaliseStepResult ev1 -> NormaliseStepResult ev2
- unwrapNewTypeStepper :: NormaliseStepper Coercion
- topNormaliseNewType_maybe :: Type -> Maybe (Coercion, Type)
- topNormaliseTypeX :: NormaliseStepper ev -> (ev -> ev -> ev) -> Type -> Maybe (ev, Type)
- decomposeCo :: Arity -> Coercion -> [Coercion]
- decomposeFunCo :: Coercion -> (Coercion, Coercion)
- getCoVar_maybe :: Coercion -> Maybe CoVar
- splitTyConAppCo_maybe :: Coercion -> Maybe (TyCon, [Coercion])
- splitAppCo_maybe :: Coercion -> Maybe (Coercion, Coercion)
- splitFunCo_maybe :: Coercion -> Maybe (Coercion, Coercion)
- splitForAllCo_maybe :: Coercion -> Maybe (TyVar, Coercion, Coercion)
- nthRole :: Role -> TyCon -> Int -> Role
- tyConRolesX :: Role -> TyCon -> [Role]
- tyConRolesRepresentational :: TyCon -> [Role]
- setNominalRole_maybe :: Coercion -> Maybe Coercion
- pickLR :: LeftOrRight -> (a, a) -> a
- isReflCo :: Coercion -> Bool
- isReflCo_maybe :: Coercion -> Maybe (Type, Role)
- isReflexiveCo :: Coercion -> Bool
- isReflexiveCo_maybe :: Coercion -> Maybe (Type, Role)
- isReflCoVar_maybe :: CoVar -> Maybe Coercion
- mkCoVar :: Name -> Type -> CoVar
- isCoVar :: Var -> Bool
- coVarName :: CoVar -> Name
- setCoVarName :: CoVar -> Name -> CoVar
- setCoVarUnique :: CoVar -> Unique -> CoVar
- isCoVar_maybe :: Coercion -> Maybe CoVar
- tyCoVarsOfCo :: Coercion -> TyCoVarSet
- tyCoVarsOfCos :: [Coercion] -> TyCoVarSet
- coVarsOfCo :: Coercion -> CoVarSet
- tyCoFVsOfCo :: Coercion -> FV
- tyCoFVsOfCos :: [Coercion] -> FV
- tyCoVarsOfCoDSet :: Coercion -> DTyCoVarSet
- coercionSize :: Coercion -> Int
- type CvSubstEnv = CoVarEnv Coercion
- emptyCvSubstEnv :: CvSubstEnv
- lookupCoVar :: TCvSubst -> Var -> Maybe Coercion
- substCo :: HasCallStack => TCvSubst -> Coercion -> Coercion
- substCos :: HasCallStack => TCvSubst -> [Coercion] -> [Coercion]
- substCoVar :: TCvSubst -> CoVar -> Coercion
- substCoVars :: TCvSubst -> [CoVar] -> [Coercion]
- substCoWith :: HasCallStack => [TyVar] -> [Type] -> Coercion -> Coercion
- substCoVarBndr :: TCvSubst -> CoVar -> (TCvSubst, CoVar)
- extendTvSubstAndInScope :: TCvSubst -> TyVar -> Type -> TCvSubst
- getCvSubstEnv :: TCvSubst -> CvSubstEnv
- liftCoSubst :: HasDebugCallStack => Role -> LiftingContext -> Type -> Coercion
- liftCoSubstTyVar :: LiftingContext -> Role -> TyVar -> Maybe Coercion
- liftCoSubstWith :: Role -> [TyCoVar] -> [Coercion] -> Type -> Coercion
- liftCoSubstWithEx :: Role -> [TyVar] -> [Coercion] -> [TyVar] -> [Type] -> (Type -> Coercion, [Type])
- emptyLiftingContext :: InScopeSet -> LiftingContext
- extendLiftingContext :: LiftingContext -> TyVar -> Coercion -> LiftingContext
- liftCoSubstVarBndrCallback :: (LiftingContext -> Type -> (Coercion, a)) -> LiftingContext -> TyVar -> (LiftingContext, TyVar, Coercion, a)
- isMappedByLC :: TyCoVar -> LiftingContext -> Bool
- mkSubstLiftingContext :: TCvSubst -> LiftingContext
- zapLiftingContext :: LiftingContext -> LiftingContext
- substForAllCoBndrCallbackLC :: Bool -> (Coercion -> Coercion) -> LiftingContext -> TyVar -> Coercion -> (LiftingContext, TyVar, Coercion)
- lcTCvSubst :: LiftingContext -> TCvSubst
- lcInScopeSet :: LiftingContext -> InScopeSet
- type LiftCoEnv = VarEnv Coercion
- data LiftingContext = LC TCvSubst LiftCoEnv
- liftEnvSubstLeft :: TCvSubst -> LiftCoEnv -> TCvSubst
- liftEnvSubstRight :: TCvSubst -> LiftCoEnv -> TCvSubst
- substRightCo :: LiftingContext -> Coercion -> Coercion
- substLeftCo :: LiftingContext -> Coercion -> Coercion
- swapLiftCoEnv :: LiftCoEnv -> LiftCoEnv
- lcSubstLeft :: LiftingContext -> TCvSubst
- lcSubstRight :: LiftingContext -> TCvSubst
- eqCoercion :: Coercion -> Coercion -> Bool
- eqCoercionX :: RnEnv2 -> Coercion -> Coercion -> Bool
- seqCo :: Coercion -> ()
- pprCo :: Coercion -> SDoc
- pprParendCo :: Coercion -> SDoc
- pprCoAxiom :: CoAxiom br -> SDoc
- pprCoAxBranch :: CoAxiom br -> CoAxBranch -> SDoc
- pprCoAxBranchHdr :: CoAxiom br -> BranchIndex -> SDoc
- tidyCo :: TidyEnv -> Coercion -> Coercion
- tidyCos :: TidyEnv -> [Coercion] -> [Coercion]
- promoteCoercion :: Coercion -> Coercion
Main data type
A Coercion
is concrete evidence of the equality/convertibility
of two types.
Instances
Data Coercion # | |
Methods gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Coercion -> c Coercion Source # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c Coercion Source # toConstr :: Coercion -> Constr Source # dataTypeOf :: Coercion -> DataType Source # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c Coercion) Source # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c Coercion) Source # gmapT :: (forall b. Data b => b -> b) -> Coercion -> Coercion Source # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Coercion -> r Source # gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Coercion -> r Source # gmapQ :: (forall d. Data d => d -> u) -> Coercion -> [u] Source # gmapQi :: Int -> (forall d. Data d => d -> u) -> Coercion -> u Source # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Coercion -> m Coercion Source # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Coercion -> m Coercion Source # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Coercion -> m Coercion Source # | |
Outputable Coercion # | |
data UnivCoProvenance Source #
For simplicity, we have just one UnivCo that represents a coercion from
some type to some other type, with (in general) no restrictions on the
type. The UnivCoProvenance specifies more exactly what the coercion really
is and why a program should (or shouldn't!) trust the coercion.
It is reasonable to consider each constructor of UnivCoProvenance
as a totally independent coercion form; their only commonality is
that they don't tell you what types they coercion between. (That info
is in the UnivCo
constructor of Coercion
.
Instances
Data UnivCoProvenance # | |
Methods gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> UnivCoProvenance -> c UnivCoProvenance Source # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c UnivCoProvenance Source # toConstr :: UnivCoProvenance -> Constr Source # dataTypeOf :: UnivCoProvenance -> DataType Source # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c UnivCoProvenance) Source # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c UnivCoProvenance) Source # gmapT :: (forall b. Data b => b -> b) -> UnivCoProvenance -> UnivCoProvenance Source # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> UnivCoProvenance -> r Source # gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> UnivCoProvenance -> r Source # gmapQ :: (forall d. Data d => d -> u) -> UnivCoProvenance -> [u] Source # gmapQi :: Int -> (forall d. Data d => d -> u) -> UnivCoProvenance -> u Source # gmapM :: Monad m => (forall d. Data d => d -> m d) -> UnivCoProvenance -> m UnivCoProvenance Source # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> UnivCoProvenance -> m UnivCoProvenance Source # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> UnivCoProvenance -> m UnivCoProvenance Source # | |
Outputable UnivCoProvenance # | |
data CoercionHole Source #
A coercion to be filled in by the type-checker. See Note [Coercion holes]
Instances
Data CoercionHole # | |
Methods gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> CoercionHole -> c CoercionHole Source # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c CoercionHole Source # toConstr :: CoercionHole -> Constr Source # dataTypeOf :: CoercionHole -> DataType Source # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c CoercionHole) Source # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c CoercionHole) Source # gmapT :: (forall b. Data b => b -> b) -> CoercionHole -> CoercionHole Source # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> CoercionHole -> r Source # gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> CoercionHole -> r Source # gmapQ :: (forall d. Data d => d -> u) -> CoercionHole -> [u] Source # gmapQi :: Int -> (forall d. Data d => d -> u) -> CoercionHole -> u Source # gmapM :: Monad m => (forall d. Data d => d -> m d) -> CoercionHole -> m CoercionHole Source # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> CoercionHole -> m CoercionHole Source # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> CoercionHole -> m CoercionHole Source # | |
Outputable CoercionHole # | |
data LeftOrRight Source #
Instances
Eq LeftOrRight # | |
Data LeftOrRight # | |
Methods gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> LeftOrRight -> c LeftOrRight Source # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c LeftOrRight Source # toConstr :: LeftOrRight -> Constr Source # dataTypeOf :: LeftOrRight -> DataType Source # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c LeftOrRight) Source # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c LeftOrRight) Source # gmapT :: (forall b. Data b => b -> b) -> LeftOrRight -> LeftOrRight Source # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> LeftOrRight -> r Source # gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> LeftOrRight -> r Source # gmapQ :: (forall d. Data d => d -> u) -> LeftOrRight -> [u] Source # gmapQi :: Int -> (forall d. Data d => d -> u) -> LeftOrRight -> u Source # gmapM :: Monad m => (forall d. Data d => d -> m d) -> LeftOrRight -> m LeftOrRight Source # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> LeftOrRight -> m LeftOrRight Source # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> LeftOrRight -> m LeftOrRight Source # | |
Outputable LeftOrRight # | |
Binary LeftOrRight # | |
Methods put_ :: BinHandle -> LeftOrRight -> IO () Source # put :: BinHandle -> LeftOrRight -> IO (Bin LeftOrRight) Source # |
Variable
Essentially a typed Name
, that may also contain some additional information
about the Var
and it's use sites.
Instances
Eq Var # | |
Data Var # | |
Methods gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Var -> c Var Source # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c Var Source # toConstr :: Var -> Constr Source # dataTypeOf :: Var -> DataType Source # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c Var) Source # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c Var) Source # gmapT :: (forall b. Data b => b -> b) -> Var -> Var Source # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Var -> r Source # gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Var -> r Source # gmapQ :: (forall d. Data d => d -> u) -> Var -> [u] Source # gmapQi :: Int -> (forall d. Data d => d -> u) -> Var -> u Source # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Var -> m Var Source # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Var -> m Var Source # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Var -> m Var Source # | |
Ord Var # | |
Outputable Var # | |
Uniquable Var # | |
HasOccName Var # | |
NamedThing Var # | |
Constructors
Nominal | |
Representational | |
Phantom |
Instances
Eq Role # | |
Data Role # | |
Methods gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Role -> c Role Source # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c Role Source # toConstr :: Role -> Constr Source # dataTypeOf :: Role -> DataType Source # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c Role) Source # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c Role) Source # gmapT :: (forall b. Data b => b -> b) -> Role -> Role Source # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Role -> r Source # gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Role -> r Source # gmapQ :: (forall d. Data d => d -> u) -> Role -> [u] Source # gmapQi :: Int -> (forall d. Data d => d -> u) -> Role -> u Source # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Role -> m Role Source # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Role -> m Role Source # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Role -> m Role Source # | |
Ord Role # | |
Outputable Role # | |
Binary Role # | |
Functions over coercions
coercionType :: Coercion -> Type Source #
coercionKind :: Coercion -> Pair Type Source #
If it is the case that
c :: (t1 ~ t2)
i.e. the kind of c
relates t1
and t2
, then coercionKind c = Pair t1 t2
.
coercionKinds :: [Coercion] -> Pair [Type] Source #
Apply coercionKind
to multiple Coercion
s
mkCoercionType :: Role -> Type -> Type -> Type Source #
Makes a coercion type from two types: the types whose equality
is proven by the relevant Coercion
coercionRole :: Coercion -> Role Source #
Retrieve the role from a coercion.
coercionKindRole :: Coercion -> (Pair Type, Role) Source #
Get a coercion's kind and role. Why both at once? See Note [Computing a coercion kind and role]
Constructing coercions
mkRepReflCo :: Type -> Coercion Source #
Make a representational reflexive coercion
mkNomReflCo :: Type -> Coercion Source #
Make a nominal reflexive coercion
mkCoVarCos :: [CoVar] -> [Coercion] Source #
mkAxInstCo :: Role -> CoAxiom br -> BranchIndex -> [Type] -> [Coercion] -> Coercion Source #
mkUnbranchedAxInstCo :: Role -> CoAxiom Unbranched -> [Type] -> [Coercion] -> Coercion Source #
mkAxInstRHS :: CoAxiom br -> BranchIndex -> [Type] -> [Coercion] -> Type Source #
mkUnbranchedAxInstRHS :: CoAxiom Unbranched -> [Type] -> [Coercion] -> Type Source #
mkAxInstLHS :: CoAxiom br -> BranchIndex -> [Type] -> [Coercion] -> Type Source #
Return the left-hand type of the axiom, when the axiom is instantiated at the types given.
mkUnbranchedAxInstLHS :: CoAxiom Unbranched -> [Type] -> [Coercion] -> Type Source #
Instantiate the left-hand side of an unbranched axiom
mkPiCo :: Role -> Var -> Coercion -> Coercion Source #
Make a forall Coercion
, where both types related by the coercion
are quantified over the same type variable.
mkSymCo :: Coercion -> Coercion Source #
Create a symmetric version of the given Coercion
that asserts
equality between the same types but in the other "direction", so
a kind of t1 ~ t2
becomes the kind t2 ~ t1
.
Arguments
:: Role | r1 |
-> Coercion | co1 :: ty1a ~r1 ty1b |
-> Type | ty1a |
-> Type | ty1b |
-> Role | r2 |
-> Coercion | co2 :: ty2a ~r2 ty2b |
-> Type | ty2a |
-> Type | ty2b |
-> Role | r3 |
-> Coercion | :: ty1a ty2a ~r3 ty1b ty2b |
Like mkAppCo
, but allows the second coercion to be other than
nominal. See Note [mkTransAppCo]. Role r3 cannot be more stringent
than either r1 or r2.
mkTyConAppCo :: HasDebugCallStack => Role -> TyCon -> [Coercion] -> Coercion Source #
Apply a type constructor to a list of coercions. It is the caller's responsibility to get the roles correct on argument coercions.
mkForAllCo :: TyVar -> Coercion -> Coercion -> Coercion Source #
Make a Coercion from a tyvar, a kind coercion, and a body coercion. The kind of the tyvar should be the left-hand kind of the kind coercion.
mkHomoForAllCos :: [TyVar] -> Coercion -> Coercion Source #
Make a Coercion quantified over a type variable; the variable has the same type in both sides of the coercion
mkHomoForAllCos_NoRefl :: [TyVar] -> Coercion -> Coercion Source #
Like mkHomoForAllCos
, but doesn't check if the inner coercion
is reflexive.
mkPhantomCo :: Coercion -> Type -> Type -> Coercion Source #
Make a phantom coercion between two types. The coercion passed in must be a nominal coercion between the kinds of the types.
mkHomoPhantomCo :: Type -> Type -> Coercion Source #
Make a phantom coercion between two types of the same kind.
toPhantomCo :: Coercion -> Coercion Source #
mkUnsafeCo :: Role -> Type -> Type -> Coercion Source #
Manufacture an unsafe coercion from thin air.
Currently (May 14) this is used only to implement the
unsafeCoerce#
primitive. Optimise by pushing
down through type constructors.
mkHoleCo :: CoercionHole -> Role -> Type -> Type -> Coercion Source #
Make a coercion from a coercion hole
Arguments
:: UnivCoProvenance | |
-> Role | role of the built coercion, "r" |
-> Type | t1 :: k1 |
-> Type | t2 :: k2 |
-> Coercion | :: t1 ~r t2 |
Make a universal coercion between two arbitrary types.
mkAxiomInstCo :: CoAxiom Branched -> BranchIndex -> [Coercion] -> Coercion Source #
Arguments
:: Role | role of the created coercion, "r" |
-> Coercion | :: phi1 ~N phi2 |
-> Coercion | g1 :: phi1 |
-> Coercion | g2 :: phi2 |
-> Coercion | :: g1 ~r g2 |
Make a "coercion between coercions".
downgradeRole :: Role -> Role -> Coercion -> Coercion Source #
Like downgradeRole_maybe
, but panics if the change isn't a downgrade.
See Note [Role twiddling functions]
maybeSubCo :: EqRel -> Coercion -> Coercion Source #
If the EqRel is ReprEq, makes a SubCo; otherwise, does nothing. Note that the input coercion should always be nominal.
mkAxiomRuleCo :: CoAxiomRule -> [Coercion] -> Coercion Source #
mkCoherenceRightCo :: Coercion -> Coercion -> Coercion infixl 5 Source #
A CoherenceCo c1 c2 applies the coercion c2 to the left-hand type in the kind of c1. This function uses sym to get the coercion on the right-hand type of c1. Thus, if c1 :: s ~ t, then mkCoherenceRightCo c1 c2 has the kind (s ~ (t |> c2)) down through type constructors. The second coercion must be representational.
mkCoherenceLeftCo :: Coercion -> Coercion -> Coercion infixl 5 Source #
An explicitly directed synonym of mkCoherenceCo. The second coercion must be representational.
castCoercionKind :: Coercion -> Coercion -> Coercion -> Coercion Source #
Creates a new coercion with both of its types casted by different casts castCoercionKind g h1 h2, where g :: t1 ~ t2, has type (t1 |> h1) ~ (t2 |> h2) The second and third coercions must be nominal.
Decomposition
instNewTyCon_maybe :: TyCon -> [Type] -> Maybe (Type, Coercion) Source #
If co :: T ts ~ rep_ty
then:
instNewTyCon_maybe T ts = Just (rep_ty, co)
Checks for a newtype, and for being saturated
type NormaliseStepper ev = RecTcChecker -> TyCon -> [Type] -> NormaliseStepResult ev Source #
A function to check if we can reduce a type by one step. Used
with topNormaliseTypeX
.
data NormaliseStepResult ev Source #
The result of stepping in a normalisation function.
See topNormaliseTypeX
.
Constructors
NS_Done | Nothing more to do |
NS_Abort | Utter failure. The outer function should fail too. |
NS_Step RecTcChecker Type ev | We stepped, yielding new bits; ^ ev is evidence; Usually a co :: old type ~ new type |
composeSteppers :: NormaliseStepper ev -> NormaliseStepper ev -> NormaliseStepper ev Source #
Try one stepper and then try the next, if the first doesn't make progress. So if it returns NS_Done, it means that both steppers are satisfied
mapStepResult :: (ev1 -> ev2) -> NormaliseStepResult ev1 -> NormaliseStepResult ev2 Source #
unwrapNewTypeStepper :: NormaliseStepper Coercion Source #
A NormaliseStepper
that unwraps newtypes, careful not to fall into
a loop. If it would fall into a loop, it produces NS_Abort
.
topNormaliseNewType_maybe :: Type -> Maybe (Coercion, Type) Source #
Sometimes we want to look through a newtype
and get its associated coercion.
This function strips off newtype
layers enough to reveal something that isn't
a newtype
. Specifically, here's the invariant:
topNormaliseNewType_maybe rec_nts ty = Just (co, ty')
then (a) co : ty0 ~ ty'
.
(b) ty' is not a newtype.
The function returns Nothing
for non-newtypes
,
or unsaturated applications
This function does *not* look through type families, because it has no access to the type family environment. If you do have that at hand, consider to use topNormaliseType_maybe, which should be a drop-in replacement for topNormaliseNewType_maybe If topNormliseNewType_maybe ty = Just (co, ty'), then co : ty ~R ty'
topNormaliseTypeX :: NormaliseStepper ev -> (ev -> ev -> ev) -> Type -> Maybe (ev, Type) Source #
A general function for normalising the top-level of a type. It continues
to use the provided NormaliseStepper
until that function fails, and then
this function returns. The roles of the coercions produced by the
NormaliseStepper
must all be the same, which is the role returned from
the call to topNormaliseTypeX
.
Typically ev is Coercion.
If topNormaliseTypeX step plus ty = Just (ev, ty')
then ty ~ev1~ t1 ~ev2~ t2 ... ~evn~ ty'
and ev = ev1 plus
ev2 plus
... plus
evn
If it returns Nothing then no newtype unwrapping could happen
getCoVar_maybe :: Coercion -> Maybe CoVar Source #
Attempts to obtain the type variable underlying a Coercion
splitTyConAppCo_maybe :: Coercion -> Maybe (TyCon, [Coercion]) Source #
Attempts to tease a coercion apart into a type constructor and the application of a number of coercion arguments to that constructor
splitAppCo_maybe :: Coercion -> Maybe (Coercion, Coercion) Source #
Attempt to take a coercion application apart.
tyConRolesRepresentational :: TyCon -> [Role] Source #
setNominalRole_maybe :: Coercion -> Maybe Coercion Source #
Converts a coercion to be nominal, if possible. See Note [Role twiddling functions]
pickLR :: LeftOrRight -> (a, a) -> a Source #
isReflCo :: Coercion -> Bool Source #
Tests if this coercion is obviously reflexive. Guaranteed to work
very quickly. Sometimes a coercion can be reflexive, but not obviously
so. c.f. isReflexiveCo
isReflCo_maybe :: Coercion -> Maybe (Type, Role) Source #
Returns the type coerced if this coercion is reflexive. Guaranteed
to work very quickly. Sometimes a coercion can be reflexive, but not
obviously so. c.f. isReflexiveCo_maybe
isReflexiveCo :: Coercion -> Bool Source #
Slowly checks if the coercion is reflexive. Don't call this in a loop, as it walks over the entire coercion.
isReflexiveCo_maybe :: Coercion -> Maybe (Type, Role) Source #
Extracts the coerced type from a reflexive coercion. This potentially walks over the entire coercion, so avoid doing this in a loop.
Coercion variables
isCoVar_maybe :: Coercion -> Maybe CoVar Source #
Extract a covar, if possible. This check is dirty. Be ashamed of yourself. (It's dirty because it cares about the structure of a coercion, which is morally reprehensible.)
Free variables
tyCoVarsOfCo :: Coercion -> TyCoVarSet Source #
tyCoVarsOfCos :: [Coercion] -> TyCoVarSet Source #
coVarsOfCo :: Coercion -> CoVarSet Source #
tyCoFVsOfCo :: Coercion -> FV Source #
tyCoFVsOfCos :: [Coercion] -> FV Source #
tyCoVarsOfCoDSet :: Coercion -> DTyCoVarSet Source #
Get a deterministic set of the vars free in a coercion
coercionSize :: Coercion -> Int Source #
Substitution
substCo :: HasCallStack => TCvSubst -> Coercion -> Coercion Source #
Substitute within a Coercion
The substitution has to satisfy the invariants described in
Note [The substitution invariant].
substCos :: HasCallStack => TCvSubst -> [Coercion] -> [Coercion] Source #
Substitute within several Coercion
s
The substitution has to satisfy the invariants described in
Note [The substitution invariant].
substCoWith :: HasCallStack => [TyVar] -> [Type] -> Coercion -> Coercion Source #
Coercion substitution, see zipTvSubst
getCvSubstEnv :: TCvSubst -> CvSubstEnv Source #
Lifting
liftCoSubst :: HasDebugCallStack => Role -> LiftingContext -> Type -> Coercion Source #
liftCoSubst role lc ty
produces a coercion (at role role
)
that coerces between lc_left(ty)
and lc_right(ty)
, where
lc_left
is a substitution mapping type variables to the left-hand
types of the mapped coercions in lc
, and similar for lc_right
.
liftCoSubstTyVar :: LiftingContext -> Role -> TyVar -> Maybe Coercion Source #
liftCoSubstWithEx :: Role -> [TyVar] -> [Coercion] -> [TyVar] -> [Type] -> (Type -> Coercion, [Type]) Source #
Arguments
:: LiftingContext | original LC |
-> TyVar | new variable to map... |
-> Coercion | ...to this lifted version |
-> LiftingContext |
Extend a lifting context with a new type mapping.
liftCoSubstVarBndrCallback :: (LiftingContext -> Type -> (Coercion, a)) -> LiftingContext -> TyVar -> (LiftingContext, TyVar, Coercion, a) Source #
isMappedByLC :: TyCoVar -> LiftingContext -> Bool Source #
Is a var in the domain of a lifting context?
zapLiftingContext :: LiftingContext -> LiftingContext Source #
Erase the environments in a lifting context
substForAllCoBndrCallbackLC :: Bool -> (Coercion -> Coercion) -> LiftingContext -> TyVar -> Coercion -> (LiftingContext, TyVar, Coercion) Source #
Like substForAllCoBndr
, but works on a lifting context
lcTCvSubst :: LiftingContext -> TCvSubst Source #
Extract the underlying substitution from the LiftingContext
lcInScopeSet :: LiftingContext -> InScopeSet Source #
Get the InScopeSet
from a LiftingContext
data LiftingContext Source #
Instances
Outputable LiftingContext # | |
substRightCo :: LiftingContext -> Coercion -> Coercion Source #
substLeftCo :: LiftingContext -> Coercion -> Coercion Source #
lcSubstLeft :: LiftingContext -> TCvSubst Source #
Comparison
eqCoercionX :: RnEnv2 -> Coercion -> Coercion -> Bool Source #
Compare two Coercion
s, with respect to an RnEnv2
Forcing evaluation of coercions
Pretty-printing
pprParendCo :: Coercion -> SDoc Source #
pprCoAxiom :: CoAxiom br -> SDoc Source #
pprCoAxBranch :: CoAxiom br -> CoAxBranch -> SDoc Source #
pprCoAxBranchHdr :: CoAxiom br -> BranchIndex -> SDoc Source #
Tidying
Other
promoteCoercion :: Coercion -> Coercion Source #
like mkKindCo, but aggressively & recursively optimizes to avoid using a KindCo constructor. The output role is nominal.