ghc-8.0.2: The GHC API

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type TcTyVar = TyVar #

type TcKind = Kind #

type TcType = Type #

newOpenFlexiTyVarTy :: TcM TcType #

Create a tyvar that can be a lifted or unlifted type.

data ExpType #

An expected type to check against during type-checking. See Note [ExpType] in TcMType, where you'll also find manipulators.


mkCheckExpType :: TcType -> ExpType #

Make an ExpType suitable for checking.

newOpenInferExpType :: TcM ExpType #

Make an ExpType suitable for inferring a type of kind * or #.

readExpType :: ExpType -> TcM TcType #

Extract a type out of an ExpType. Otherwise, panics.

readExpType_maybe :: ExpType -> TcM (Maybe TcType) #

Extract a type out of an ExpType, if one exists. But one should always exist. Unless you're quite sure you know what you're doing.

writeExpType :: ExpType -> TcType -> TcM () #

Write into an ExpType. It must be an Infer.

expTypeToType :: ExpType -> TcM TcType #

Extracts the expected type if there is one, or generates a new TauTv if there isn't.

checkingExpType_maybe :: ExpType -> Maybe TcType #

Returns the expected type when in checking mode.

checkingExpType :: String -> ExpType -> TcType #

Returns the expected type when in checking mode. Panics if in inference mode.

tauifyExpType :: ExpType -> TcM ExpType #

Turn a (Infer hole) type into a (Check alpha), where alpha is a fresh unificaiton variable

emitWanted :: CtOrigin -> TcPredType -> TcM EvTerm #

Emits a new Wanted. Deals with both equalities and non-equalities.

emitWantedEq :: CtOrigin -> TypeOrKind -> Role -> TcType -> TcType -> TcM Coercion #

Emits a new equality constraint

emitWantedEvVar :: CtOrigin -> TcPredType -> TcM EvVar #

Creates a new EvVar and immediately emits it as a Wanted. No equality predicates here.

fillCoercionHole :: CoercionHole -> Coercion -> TcM () #

Put a value in a coercion hole

isFilledCoercionHole :: CoercionHole -> TcM Bool #

Is a coercion hole filled in?

unpackCoercionHole :: CoercionHole -> TcM Coercion #

Retrieve the contents of a coercion hole. Panics if the hole is unfilled

unpackCoercionHole_maybe :: CoercionHole -> TcM (Maybe Coercion) #

Retrieve the contents of a coercion hole, if it is filled

checkCoercionHole :: Coercion -> CoercionHole -> Role -> Type -> Type -> TcM Coercion #

Check that a coercion is appropriate for filling a hole. (The hole itself is needed only for printing. NB: This must be lazy in the coercion, as it's used in TcHsSyn in the presence of knots. Always returns the checked coercion, but this return value is necessary so that the input coercion is forced only when the output is forced.

tcInstType #


:: ([TyVar] -> TcM (TCvSubst, [TcTyVar]))

How to instantiate the type variables

-> TcType

Type to instantiate

-> TcM ([TcTyVar], TcThetaType, TcType)

Result (type vars, preds (incl equalities), rho)

instSkolTyCoVars :: (Unique -> Name -> Kind -> TyCoVar) -> [TyVar] -> TcRnIf gbl lcl (TCvSubst, [TyCoVar]) #

freshenTyVarBndrs :: [TyVar] -> TcRnIf gbl lcl (TCvSubst, [TyVar]) #

Give fresh uniques to a bunch of TyVars, but they stay as TyVars, rather than becoming TcTyVars Used in FamInst.newFamInst, and Inst.newClsInst

freshenCoVarBndrsX :: TCvSubst -> [CoVar] -> TcRnIf gbl lcl (TCvSubst, [CoVar]) #

Give fresh uniques to a bunch of CoVars Used in FamInst.newFamInst

mkTypeErrorThing :: TcType -> ErrorThing #

Make an ErrorThing storing a type.

mkTypeErrorThingArgs :: TcType -> Int -> ErrorThing #

Make an ErrorThing storing a type, with some extra args known about

tidyCt :: TidyEnv -> Ct -> Ct #

zonkTcTypeAndSplitDepVars :: TcType -> TcM TcDepVars #

Zonk a type and call splitDepVarsOfType on it. Works within the knot.

zonkQuantifiedTyVarOrType :: TcTyVar -> TcM (Either TcTyVar TcType) #

Like zonkQuantifiedTyVar, but if zonking reveals that the tyvar should become a type (when defaulting a RuntimeRep var to PtrRepLifted), it returns the type instead.

defaultKindVar :: TcTyVar -> TcM Kind #

Take an (unconstrained) meta tyvar and default it. Works only on vars of type RuntimeRep and of type *. For other kinds, it issues an error. See Note [Defaulting with -XNoPolyKinds]

zonkCo :: Coercion -> TcM Coercion #

Zonk a coercion -- really, just zonk any types in the coercion

zonkTcTypeMapper :: TyCoMapper () TcM #

A suitable TyCoMapper for zonking a type inside the knot, and before all metavars are filled in.

zonkCt :: Ct -> TcM Ct #

tcGetGlobalTyCoVars :: TcM TcTyVarSet #

tcGetGlobalTyCoVars returns a fully-zonked set of *scoped* tyvars free in the environment. To improve subsequent calls to the same function it writes the zonked set back into the environment. Note that this returns all variables free in anything (term-level or type-level) in scope. We thus don't have to worry about clashes with things that are not in scope, because if they are reachable, then they'll be returned here.