GHC.Tc.Plugin

This module provides an interface for typechecker plugins to access select functions of the TcM, principally those to do with reading parts of the state.

Basic TcPluginM functionality

data TcPluginM a

TcPluginM is the monad in which type-checking plugins operate.

Instances

MonadFail TcPluginM

Defined in GHC.Tc.Types

Methods

fail :: String -> TcPluginM a

Applicative TcPluginM

Defined in GHC.Tc.Types

Methods

pure :: a -> TcPluginM a

(<*>) :: TcPluginM (a -> b) -> TcPluginM a -> TcPluginM b

liftA2 :: (a -> b -> c) -> TcPluginM a -> TcPluginM b -> TcPluginM c

(*>) :: TcPluginM a -> TcPluginM b -> TcPluginM b

(<*) :: TcPluginM a -> TcPluginM b -> TcPluginM a

Functor TcPluginM

Defined in GHC.Tc.Types

Methods

fmap :: (a -> b) -> TcPluginM a -> TcPluginM b

(<$) :: a -> TcPluginM b -> TcPluginM a

Monad TcPluginM

Defined in GHC.Tc.Types

Methods

(>>=) :: TcPluginM a -> (a -> TcPluginM b) -> TcPluginM b

(>>) :: TcPluginM a -> TcPluginM b -> TcPluginM b

return :: a -> TcPluginM a

tcPluginIO :: IO a -> TcPluginM a

Perform some IO, typically to interact with an external tool.

tcPluginTrace :: String -> SDoc -> TcPluginM ()

Output useful for debugging the compiler.

unsafeTcPluginTcM :: TcM a -> TcPluginM a

This function provides an escape for direct access to the TcM monad. It should not be used lightly, and the provided TcPluginM API should be favoured instead.

Finding Modules and Names

data FindResult

The result of searching for an imported module.

NB: FindResult manages both user source-import lookups (which can result in Module) as well as direct imports for interfaces (which always result in InstalledModule).

Constructors

Found ModLocation Module

The module was found

NoPackage Unit

The requested unit was not found

FoundMultiple [(Module, ModuleOrigin)]

_Error_: both in multiple packages

NotFound

Not found

Fields

• fr_paths :: [FilePath]

  Places where I looked

• fr_pkg :: Maybe Unit

  Just p => module is in this unit's manifest, but couldn't find the .hi file

• fr_mods_hidden :: [Unit]

  Module is in these units, but the *module* is hidden

• fr_pkgs_hidden :: [Unit]

  Module is in these units, but the *unit* is hidden

• fr_unusables :: [(Unit, UnusableUnitReason)]

  Module is in these units, but it is unusable

• fr_suggestions :: [ModuleSuggestion]

  Possible mis-spelled modules

findImportedModule :: ModuleName -> PkgQual -> TcPluginM FindResult

lookupOrig :: Module -> OccName -> TcPluginM Name

Looking up Names in the typechecking environment

tcLookupGlobal :: Name -> TcPluginM TyThing

tcLookupTyCon :: Name -> TcPluginM TyCon

tcLookupDataCon :: Name -> TcPluginM DataCon

tcLookupClass :: Name -> TcPluginM Class

tcLookup :: Name -> TcPluginM TcTyThing

tcLookupId :: Name -> TcPluginM Id

Getting the TcM state

getTopEnv :: TcPluginM HscEnv

getTargetPlatform :: TcPluginM Platform

getEnvs :: TcPluginM (TcGblEnv, TcLclEnv)

getInstEnvs :: TcPluginM InstEnvs

getFamInstEnvs :: TcPluginM (FamInstEnv, FamInstEnv)

matchFam :: TyCon -> [Type] -> TcPluginM (Maybe Reduction)

Type variables

newUnique :: TcPluginM Unique

newFlexiTyVar :: Kind -> TcPluginM TcTyVar

isTouchableTcPluginM :: TcTyVar -> TcPluginM Bool

Zonking

zonkTcType :: TcType -> TcPluginM TcType

Confused by zonking? See Note [What is zonking?] in GHC.Tc.Zonk.Type.

zonkCt :: Ct -> TcPluginM Ct

Creating constraints

newWanted :: CtLoc -> PredType -> TcPluginM CtEvidence

Create a new Wanted constraint with the given CtLoc.

newGiven :: EvBindsVar -> CtLoc -> PredType -> EvExpr -> TcPluginM CtEvidence

Create a new given constraint, with the supplied evidence.

This should only be invoked within tcPluginSolve.

newCoercionHole :: PredType -> TcPluginM CoercionHole

Create a fresh coercion hole. This should only be invoked within tcPluginSolve.

Manipulating evidence bindings

newEvVar :: PredType -> TcPluginM EvVar

Create a fresh evidence variable.

This should only be invoked within tcPluginSolve.

setEvBind :: EvBindsVar -> EvBind -> TcPluginM ()

Bind an evidence variable.

This should only be invoked within tcPluginSolve.