| Safe Haskell | Unsafe |
|---|---|
| Language | Haskell2010 |
Language.Haskell.TH.CodeT.Unsafe
Synopsis
- newtype CodeT q a = UnsafeCodeT (q Type)
- unsafeCodeTCoerce :: Quote q => q Type -> CodeT q a
- unTypeCodeT :: CodeT m a -> m Type
- appCodeT :: Quote m => CodeT m f -> CodeT m x -> CodeT m (f x)
- sigCode :: Quote q => Code q a -> CodeT q a -> Code q a
- sigCodeT :: Quote q => CodeT q (a :: k) -> CodeT q k -> CodeT q a
- type CodeTQ = CodeT Q
- unsafeCodeTName :: Quote m => Name -> CodeT m a
- unsafeCodeTNameD :: String -> String -> String -> forall m. Quote m => CodeT m a
- unsafeCodeTNameTC :: String -> String -> String -> forall m. Quote m => CodeT m a
- class LiftT a where
CodeT
CodeT is to Type what Code is to Exp.
Because current GHC Haskell doesn't have true dependent types,
we often use singletons pattern to emulate them.
To a first approximation CodeT q a -> ...forall (a :: .Code q Type) -> ...
There aren't typed type quotes, i.e. we cannot write [t|| Int ||],
instead we have to resort to unsafe interface for now:
>>>let ty = UnsafeCodeT [t| Int |] :: Quote q => CodeT q Int>>>unTypeCodeT ty >>= print . pprGHC.Types.Int
... or we can "safely" create many CodeT values using LiftT type-class:
>>>let ty' = codeT :: Quote q => CodeT q Int>>>unTypeCodeT ty' >>= print . pprGHC.Types.Int
Constructors
| UnsafeCodeT (q Type) | Unsafely convert an untyped code representation into a typed code representation. Prefer using |
unsafeCodeTCoerce :: Quote q => q Type -> CodeT q a Source #
Unsafely convert an untyped code representation into a typed code representation.
unTypeCodeT :: CodeT m a -> m Type Source #
Extract the untyped representation from the typed representation.
appCodeT :: Quote m => CodeT m f -> CodeT m x -> CodeT m (f x) Source #
>>>let ty = appCodeT (codeT @Maybe) (codeT @Char)>>>unTypeCodeT ty >>= print . pprGHC...Maybe GHC.Types.Char
sigCode :: Quote q => Code q a -> CodeT q a -> Code q a Source #
>>>let e = sigCode [|| 'x' ||] codeT>>>unTypeCode e >>= print . ppr'x' :: GHC.Types.Char
sigCodeT :: Quote q => CodeT q (a :: k) -> CodeT q k -> CodeT q a Source #
>>>let ty = sigCodeT (codeT @Bool) codeT>>>unTypeCodeT ty >>= print . ppr(GHC.Types.Bool :: GHC.Prim.TYPE (GHC.Types.BoxedRep GHC.Types.Lifted))
unsafeCodeTName :: Quote m => Name -> CodeT m a Source #
Unsafely convert a (type) name into a typed code representation.
The namespace of Name is not checked.
>>>let ty = unsafeCodeTName ''Bool>>>unTypeCodeT ty >>= print . pprGHC.Types.Bool
unsafeCodeTNameD :: String -> String -> String -> forall m. Quote m => CodeT m a Source #
Unsafely create a data constructor name and convert it into a typed code representation.
unsafeCodeTNameTC :: String -> String -> String -> forall m. Quote m => CodeT m a Source #
Unsafely create a type constructor name and convert it into a typed code representation.
LiftT
Implicitly create CodeT values.
This packages provides some LiftT instances for types in GHC bundled libs.
There is no instance for Constraint, as Constraint is not apart from Type.
See the GHC issue https://gitlab.haskell.org/ghc/ghc/-/issues/24279.
The codet-plugin can automatically
create instances for type constructors. (The provided f x instance does most of the work).