ghc-9.0.2: The GHC API

GHC.Tc.Errors.Hole

Synopsis

# Documentation

Arguments

 :: TidyEnv The tidy_env for zonking -> [Implication] Enclosing implications for givens -> [Ct] The unsolved simple constraints in the implication for the hole. -> Hole -> TcM (TidyEnv, SDoc)

Arguments

 :: TypedHole The hole to check against -> TcSigmaType The type to check against (possibly modified, e.g. refined) -> TcSigmaType The type to check whether fits. -> TcM (Bool, HsWrapper) Whether it was a match, and the wrapper from hole_ty to ty.

A tcSubsumes which takes into account relevant constraints, to fix trac #14273. This makes sure that when checking whether a type fits the hole, the type has to be subsumed by type of the hole as well as fulfill all constraints on the type of the hole.

withoutUnification :: FV -> TcM a -> TcM a Source #

Takes a list of free variables and restores any Flexi type variables in free_vars after the action is run.

Reports whether first type (ty_a) subsumes the second type (ty_b), discarding any errors. Subsumption here means that the ty_b can fit into the ty_a, i.e. tcSubsumes a b == True if b is a subtype of a.

Checks whether a MetaTyVar is flexible or not.

Arguments

 :: Maybe Int How many we should output, if limited -> TypedHole The hole to filter against -> (TcType, [TcTyVar]) The type to check for fits and a list of refinement variables (free type variables in the type) for emulating additional holes. -> [HoleFitCandidate] The candidates to check whether fit. -> TcM (Bool, [HoleFit]) We return whether or not we stopped due to hitting the limit and the fits we found.

tcFilterHoleFits filters the candidates by whether, given the implications and the relevant constraints, they can be made to match the type by running the type checker. Stops after finding limit matches.

Constructors

 HFDC FieldsshowWrap :: Bool showWrapVars :: Bool showType :: Bool showProv :: Bool showMatches :: Bool

Constructors

 HFSNoSorting HFSBySize HFSBySubsumption

#### Instances

Instances details
 Source # Instance detailsDefined in GHC.Tc.Errors.Hole Methods Source # Instance detailsDefined in GHC.Tc.Errors.Hole Methods

relevantCts :: Type -> [Ct] -> [Ct] Source #

Sort by size uses as a measure for relevance the sizes of the different types needed to instantiate the fit to the type of the hole. This is much quicker than sorting by subsumption, and gives reasonable results in most cases.

A HoleFitPlugin is a pair of candidate and fit plugins.

Constructors

 HoleFitPlugin Fields

HoleFitPluginR adds a TcRef to hole fit plugins so that plugins can track internal state. Note the existential quantification, ensuring that the state cannot be modified from outside the plugin.

Constructors

 forall s. HoleFitPluginR FieldshfPluginInit :: TcM (TcRef s)Initializes the TcRef to be passed to the pluginhfPluginRun :: TcRef s -> HoleFitPluginThe function defining the plugin itselfhfPluginStop :: TcRef s -> TcM ()Cleanup of state, guaranteed to be called even on error