ghc-8.8.1: The GHC API
Safe HaskellNone




tcDerivStrategy Source #


:: forall a. Maybe (DerivStrategy GhcRn)

The deriving strategy

-> TcM ([TyVar], a)

The thing to typecheck within the context of the deriving strategy, which might quantify some type variables of its own.

-> TcM (Maybe (DerivStrategy GhcTc), [TyVar], a)

The typechecked deriving strategy, all quantified tyvars, and the payload of the typechecked thing.

Typecheck something within the context of a deriving strategy. This is of particular importance when the deriving strategy is via. For instance:

deriving via (S a) instance C (T a)

We need to typecheck S a, and moreover, we need to extend the tyvar environment with a before typechecking C (T a), since S a quantified the type variable a.

tcHsTypeApp :: LHsWcType GhcRn -> Kind -> TcM Type Source #

Type-check a visible type application

data ContextKind Source #

Describes the kind expected in a certain context.


TheKind Kind

a specific kind


any kind will do


something of the form TYPE _

bindTyClTyVars :: Name -> ([TyConBinder] -> Kind -> TcM a) -> TcM a Source #

Used for the type variables of a type or class decl in the "kind checking" and "type checking" pass, but not in the initial-kind run.

kcLHsQTyVars Source #


:: Name

of the thing being checked

-> TyConFlavour

What sort of TyCon is being checked

-> Bool

True = the decl being checked has a CUSK

-> LHsQTyVars GhcRn 
-> TcM Kind

The result kind

-> TcM TcTyCon

A suitably-kinded TcTyCon

Kind-check a LHsQTyVars. If the decl under consideration has a complete, user-supplied kind signature (CUSK), generalise the result. Used in getInitialKind (for tycon kinds and other kinds) and in kind-checking (but not for tycon kinds, which are checked with tcTyClDecls). See Note [CUSKs: complete user-supplied kind signatures] in HsDecls.

This function does not do telescope checking.

tcWildCardBinders :: [Name] -> ([(Name, TcTyVar)] -> TcM a) -> TcM a Source #

tcInferApps Source #


:: TcTyMode 
-> LHsType GhcRn

Function (for printing only)

-> TcType


-> TcKind

Function kind (zonked)

-> [LHsTypeArg GhcRn]


-> TcM (TcType, TcKind)

(f args, args, result kind) Precondition: tcTypeKind fun_ty = fun_ki Reason: we will return a type application like (fun_ty arg1 ... argn), and that type must be well-kinded See Note [The tcType invariant] Postcondition: Result kind is zonked.

Apply a type of a given kind to a list of arguments. This instantiates invisible parameters as necessary. Always consumes all the arguments, using matchExpectedFunKind as necessary. This takes an optional VarEnv Kind which maps kind variables to kinds.- These kinds should be used to instantiate invisible kind variables; they come from an enclosing class for an associated type/data family.

failIfEmitsConstraints :: TcM a -> TcM a Source #

If the inner action emits constraints, report them as errors and fail; otherwise, propagates the return value. Useful as a wrapper around tcImplicitTKBndrs, which uses solveLocalEqualities, when there won't be another chance to solve constraints

solveEqualities :: TcM a -> TcM a Source #

Type-check a thing that emits only equality constraints, then solve those constraints. Fails outright if there is trouble. Use this if you're not going to get another crack at solving (because, e.g., you're checking a datatype declaration)

typeLevelMode :: TcTyMode Source #

kindLevelMode :: TcTyMode Source #

checkExpectedKind Source #


:: HasDebugCallStack 
=> RequireSaturation

Do we require all type families to be saturated?

-> SDoc

type we're checking (for printing)

-> TcType

type we're checking

-> TcKind

the known kind of that type

-> TcKind

the expected kind

-> TcM TcType 

This instantiates invisible arguments for the type being checked if it must be saturated and is not yet saturated. It then calls and uses the result from checkExpectedKindX to build the final type Obeys Note [The tcType invariant]

data RequireSaturation Source #

Do we require type families to be saturated?


Instances details
Outputable RequireSaturation Source # 
Instance details

Defined in TcHsType

zonkPromoteType :: TcType -> TcM TcType Source #

Whenever a type is about to be added to the environment, it's necessary to make sure that any free meta-tyvars in the type are promoted to the current TcLevel. (They might be at a higher level due to the level-bumping in tcExplicitTKBndrs, for example.) This function both zonks *and* promotes. Why at the same time? See Note [Recipe for checking a signature]

funAppCtxt :: (Outputable fun, Outputable arg) => fun -> arg -> Int -> SDoc Source #

Make an appropriate message for an error in a function argument. Used for both expressions and types.

addTyConFlavCtxt :: Name -> TyConFlavour -> TcM a -> TcM a Source #

Add a "In the data declaration for T" or some such.