TcUnify

Documentation

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

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

Sometimes we don't have a HsExpr Name to hand, and this is more convenient.

tcSkolemise

Arguments

:: UserTypeCtxt

-> TcSigmaType

-> ([TcTyVar] -> TcType -> TcM result)

These are only ever used for scoped type variables.

-> TcM (HsWrapper, result)

The expression has type: spec_ty -> expected_ty

Take an "expected type" and strip off quantifiers to expose the type underneath, binding the new skolems for the thing_inside. The returned HsWrapper has type specific_ty -> expected_ty.

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

Variant of tcSkolemise that takes an ExpType

tcSubTypeHR

Arguments

:: CtOrigin

of the actual type

-> Maybe (HsExpr GhcRn)

If present, it has type ty_actual

-> TcSigmaType

-> ExpRhoType

-> TcM HsWrapper

Call this variant when you are in a higher-rank situation and you know the right-hand type is deeply skolemised.

tcSubTypeO

Arguments

:: CtOrigin

of the actual type

-> UserTypeCtxt

of the expected type

-> TcSigmaType

-> ExpRhoType

-> TcM HsWrapper

tcSubType_NC :: UserTypeCtxt -> TcSigmaType -> TcSigmaType -> TcM HsWrapper

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

tcSubTypeDS_NC_O :: CtOrigin -> UserTypeCtxt -> Maybe (HsExpr GhcRn) -> TcSigmaType -> ExpRhoType -> TcM HsWrapper

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

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

checkTvConstraints :: SkolemInfo -> Maybe SDoc -> TcM ([TcTyVar], result) -> TcM ([TcTyVar], result)

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

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

unifyType

Arguments

:: Maybe (HsExpr GhcRn)

If present, has type ty1

-> TcTauType

-> TcTauType

-> TcM TcCoercionN

unifyKind :: Maybe (HsType GhcRn) -> TcKind -> TcKind -> TcM CoercionN

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

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

swapOverTyVars :: TcTyVar -> TcTyVar -> Bool

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

tcInferInst :: (ExpRhoType -> TcM a) -> TcM (a, TcRhoType)

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

Infer a type using a fresh ExpType See also Note [ExpType] in TcMType Does not attempt to instantiate the inferred type

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

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

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

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

matchActualFunTys :: SDoc -> CtOrigin -> Maybe (HsExpr GhcRn) -> Arity -> TcSigmaType -> TcM (HsWrapper, [TcSigmaType], TcSigmaType)

matchActualFunTysPart :: SDoc -> CtOrigin -> Maybe (HsExpr GhcRn) -> Arity -> TcSigmaType -> [TcSigmaType] -> Arity -> TcM (HsWrapper, [TcSigmaType], TcSigmaType)

Variant of matchActualFunTys that works when supplied only part (that is, to the right of some arrows) of the full function type

matchExpectedFunKind

Arguments

:: Outputable fun

=> fun

type, only for errors

-> TcKind

function kind

-> TcM (Coercion, TcKind, TcKind)

co :: old_kind ~ arg -> res

Breaks apart a function kind into its pieces.

metaTyVarUpdateOK :: DynFlags -> TcTyVar -> TcType -> Maybe TcType

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

data OccCheckResult a

Constructors

OC_OK a

OC_Bad

OC_Occurs

Instances

Monad OccCheckResult

Defined in TcUnify

Methods

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

(>>) :: OccCheckResult a -> OccCheckResult b -> OccCheckResult b

return :: a -> OccCheckResult a

Functor OccCheckResult

Defined in TcUnify

Methods

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

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

Applicative OccCheckResult

Defined in TcUnify

Methods

pure :: a -> OccCheckResult a

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

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

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

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