Documentation

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

Type-check a visible type application

Describes the kind expected in a certain context.

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.

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.

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

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

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)

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)

A description of whether something is a

• data or newtype (DataDeclSort)
• data instance or newtype instance (DataInstanceSort)
• data family (DataFamilySort)

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

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]

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

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