ghc-8.10.6: The GHC API
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tcDerivStrategy Source #


:: Maybe (LDerivStrategy GhcRn)

The deriving strategy

-> TcM (Maybe (LDerivStrategy GhcTc), [TyVar])

The typechecked deriving strategy and the tyvars that it binds (if using ViaStrategy).

Typecheck a deriving strategy. For most deriving strategies, this is a no-op, but for the via strategy, this requires typechecking the via type.

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.

data SAKS_or_CUSK Source #


SAKS Kind 


Instances details
Outputable SAKS_or_CUSK # 
Instance details

Defined in TcHsType

kcDeclHeader Source #


:: InitialKindStrategy 
-> Name

of the thing being checked

-> TyConFlavour

What sort of TyCon is being checked

-> LHsQTyVars GhcRn

Binders in the header

-> TcM ContextKind

The result kind

-> TcM TcTyCon

A suitably-kinded TcTyCon

tcInferApps Source #


:: TcTyMode 
-> LHsType GhcRn

Function (for printing only)

-> TcType


-> [LHsTypeArg GhcRn]


-> TcM (TcType, TcKind)

(f args, args, result kind)

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.

tcInferApps also arranges to saturate any trailing invisible arguments of a type-family application, which is usually the right thing to do tcInferApps_nosat does not do this saturation; it is used only by ":kind" in GHCi

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 #

kindGeneralizeAll :: TcType -> TcM [KindVar] Source #

Specialized version of kindGeneralizeSome, but where all variables can be generalized. Use this variant when you can be sure that no more constraints on the type's metavariables will arise or be solved.

kindGeneralizeSome Source #


:: (TcTyVar -> Bool) 
-> TcType

needn't be zonked

-> TcM [KindVar] 

Generalize some of the free variables in the given type. All such variables should be *kind* variables; any type variables should be explicitly quantified (with a forall) before now. The supplied predicate says which free variables to quantify. But in all cases, generalize only those variables whose TcLevel is strictly greater than the ambient level. This "strictly greater than" means that you likely need to push the level before creating whatever type gets passed here. Any variable whose level is greater than the ambient level but is not selected to be generalized will be promoted. (See [Promoting unification variables] in TcSimplify and Note [Recipe for checking a signature].) The resulting KindVar are the variables to quantify over, in the correct, well-scoped order. They should generally be Inferred, not Specified, but that's really up to the caller of this function.

kindGeneralizeNone :: TcType -> TcM () Source #

Specialized version of kindGeneralizeSome, but where no variables can be generalized, but perhaps some may neeed to be promoted. Use this variant when it is unknowable whether metavariables might later be constrained.

To see why this promotion is needed, see Note [Recipe for checking a signature], and especially Note [Promotion in signatures].

checkExpectedKind_pp Source #


:: HasDebugCallStack 
=> SDoc

The thing we are checking

-> TcType

type we're checking

-> TcKind

the known kind of that type

-> TcKind

the expected kind

-> TcM TcType 

checkDataKindSig :: DataSort -> Kind -> TcM () Source #

Checks that the return kind in a data declaration's kind signature is permissible. There are three cases:

If dealing with a data, newtype, data instance, or newtype instance declaration, check that the return kind is Type.

If the declaration is a newtype or newtype instance and the UnliftedNewtypes extension is enabled, this check is slightly relaxed so that a return kind of the form TYPE r (for some r) is permitted. See Note [Implementation of UnliftedNewtypes] in TcTyClsDecls.

If dealing with a data family declaration, check that the return kind is either of the form:

  1. TYPE r (for some r), or
  2. k (where k is a bare kind variable; see #12369)

data DataSort Source #

A description of whether something is a

At present, this data type is only consumed by checkDataKindSig.

checkClassKindSig :: Kind -> TcM () Source #

Checks that the result kind of a class is exactly Constraint, rejecting type synonyms and type families that reduce to Constraint. See #16826.

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.