GHC.Tc.Utils.Unify

Type subsumption and unification

Documentation

tcWrapResult :: HsExpr GhcRn -> HsExpr GhcTc -> TcSigmaType -> ExpRhoType -> TcM (HsExpr GhcTc)

tcWrapResultO :: CtOrigin -> HsExpr GhcRn -> HsExpr GhcTc -> TcSigmaType -> ExpRhoType -> TcM (HsExpr GhcTc)

tcWrapResultMono :: HsExpr GhcRn -> HsExpr GhcTc -> TcRhoType -> ExpRhoType -> TcM (HsExpr GhcTc)

tcSkolemise

Arguments

:: UserTypeCtxt

-> TcSigmaType

-> (TcType -> TcM result)

-> TcM (HsWrapper, result)

The wrapper has type: spec_ty ~> expected_ty See Note [Skolemisation] for the differences between tcSkolemiseScoped and tcSkolemise

tcSkolemiseScoped

Arguments

:: UserTypeCtxt

-> TcSigmaType

-> (TcType -> TcM result)

-> TcM (HsWrapper, result)

The wrapper has type: spec_ty ~> expected_ty See Note [Skolemisation] for the differences between tcSkolemiseScoped and tcSkolemise

tcSkolemiseET :: UserTypeCtxt -> ExpSigmaType -> (ExpRhoType -> TcM result) -> TcM (HsWrapper, result)

Variant of tcSkolemise that takes an ExpType

tcSubType :: CtOrigin -> UserTypeCtxt -> TcSigmaType -> ExpRhoType -> TcM HsWrapper

tcSubTypeSigma :: UserTypeCtxt -> TcSigmaType -> TcSigmaType -> TcM HsWrapper

tcSubTypePat :: CtOrigin -> UserTypeCtxt -> ExpSigmaType -> TcSigmaType -> TcM HsWrapper

tcSubMult :: CtOrigin -> Mult -> Mult -> TcM HsWrapper

checkConstraints :: SkolemInfo -> [TcTyVar] -> [EvVar] -> TcM result -> TcM (TcEvBinds, result)

checkTvConstraints :: SkolemInfo -> [TcTyVar] -> TcM result -> TcM result

buildImplicationFor :: TcLevel -> SkolemInfo -> [TcTyVar] -> [EvVar] -> WantedConstraints -> TcM (Bag Implication, TcEvBinds)

buildTvImplication :: SkolemInfo -> [TcTyVar] -> TcLevel -> WantedConstraints -> TcM Implication

emitResidualTvConstraint :: SkolemInfo -> [TcTyVar] -> TcLevel -> WantedConstraints -> TcM ()

unifyType

Arguments

:: Maybe SDoc

If present, the thing that has type ty1

-> TcTauType

-> TcTauType

-> TcM TcCoercionN

unifyKind :: Maybe SDoc -> TcKind -> TcKind -> TcM CoercionN

uType :: TypeOrKind -> CtOrigin -> TcType -> TcType -> TcM CoercionN

promoteTcType :: TcLevel -> TcType -> TcM (TcCoercionN, TcType)

swapOverTyVars :: Bool -> TcTyVar -> TcTyVar -> Bool

canSolveByUnification :: TcLevel -> TcTyVar -> TcType -> Bool

tcInfer :: (ExpSigmaType -> TcM a) -> TcM (a, TcSigmaType)

Infer a type using a fresh ExpType See also Note [ExpType] in GHC.Tc.Utils.TcMType

matchExpectedListTy :: TcRhoType -> TcM (TcCoercionN, TcRhoType)

matchExpectedTyConApp :: TyCon -> TcRhoType -> TcM (TcCoercionN, [TcSigmaType])

matchExpectedAppTy :: TcRhoType -> TcM (TcCoercion, (TcSigmaType, TcSigmaType))

matchExpectedFunTys :: forall a. SDoc -> UserTypeCtxt -> Arity -> ExpRhoType -> ([Scaled ExpSigmaType] -> ExpRhoType -> TcM a) -> TcM (HsWrapper, a)

matchExpectedFunKind

Arguments

:: Outputable fun

=> fun

type, only for errors

-> Arity

n: number of desired arrows

-> TcKind

fun_ kind

-> TcM Coercion

co :: fun_kind ~ (arg1 -> ... -> argn -> res)

Breaks apart a function kind into its pieces.

matchActualFunTySigma :: SDoc -> Maybe SDoc -> (Arity, [Scaled TcSigmaType]) -> TcRhoType -> TcM (HsWrapper, Scaled TcSigmaType, TcSigmaType)

matchActualFunTySigma does looks for just one function arrow returning an uninstantiated sigma-type

matchActualFunTysRho :: SDoc -> CtOrigin -> Maybe SDoc -> Arity -> TcSigmaType -> TcM (HsWrapper, [Scaled TcSigmaType], TcRhoType)

metaTyVarUpdateOK :: DynFlags -> TcTyVar -> TcType -> MetaTyVarUpdateResult TcType

occCheckForErrors :: DynFlags -> TcTyVar -> Type -> MetaTyVarUpdateResult ()

data MetaTyVarUpdateResult a

Constructors

MTVU_OK a

MTVU_Bad

MTVU_HoleBlocker

MTVU_Occurs

Instances

Monad MetaTyVarUpdateResult

Defined in GHC.Tc.Utils.Unify

Methods

(>>=) :: MetaTyVarUpdateResult a -> (a -> MetaTyVarUpdateResult b) -> MetaTyVarUpdateResult b

(>>) :: MetaTyVarUpdateResult a -> MetaTyVarUpdateResult b -> MetaTyVarUpdateResult b

return :: a -> MetaTyVarUpdateResult a

Functor MetaTyVarUpdateResult

Defined in GHC.Tc.Utils.Unify

Methods

fmap :: (a -> b) -> MetaTyVarUpdateResult a -> MetaTyVarUpdateResult b

(<$) :: a -> MetaTyVarUpdateResult b -> MetaTyVarUpdateResult a

Applicative MetaTyVarUpdateResult

Defined in GHC.Tc.Utils.Unify

Methods

pure :: a -> MetaTyVarUpdateResult a

(<*>) :: MetaTyVarUpdateResult (a -> b) -> MetaTyVarUpdateResult a -> MetaTyVarUpdateResult b

liftA2 :: (a -> b -> c) -> MetaTyVarUpdateResult a -> MetaTyVarUpdateResult b -> MetaTyVarUpdateResult c

(*>) :: MetaTyVarUpdateResult a -> MetaTyVarUpdateResult b -> MetaTyVarUpdateResult b

(<*) :: MetaTyVarUpdateResult a -> MetaTyVarUpdateResult b -> MetaTyVarUpdateResult a

Outputable a => Outputable (MetaTyVarUpdateResult a)

Defined in GHC.Tc.Utils.Unify

Methods

ppr :: MetaTyVarUpdateResult a -> SDoc