{-# LANGUAGE Trustworthy #-} {-# LANGUAGE NoImplicitPrelude , RankNTypes , ExistentialQuantification #-} {-# OPTIONS_HADDOCK hide #-} ----------------------------------------------------------------------------- -- | -- Module : GHC.Desugar -- Copyright : (c) The University of Glasgow, 2007 -- License : see libraries/base/LICENSE -- -- Maintainer : cvs-ghc@haskell.org -- Stability : internal -- Portability : non-portable (GHC extensions) -- -- Support code for desugaring in GHC -- ----------------------------------------------------------------------------- module GHC.Desugar ((>>>), AnnotationWrapper(..), toAnnotationWrapper) where import Control.Arrow (Arrow(..)) import Control.Category ((.)) import Data.Data (Data) -- A version of Control.Category.>>> overloaded on Arrow (>>>) :: forall arr. Arrow arr => forall a b c. arr a b -> arr b c -> arr a c -- NB: the type of this function is the "shape" that GHC expects -- in tcInstClassOp. So don't put all the foralls at the front! -- Yes, this is a bit grotesque, but heck it works and the whole -- arrows stuff needs reworking anyway! f >>> g = g . f -- A wrapper data type that lets the typechecker get at the appropriate dictionaries for an annotation data AnnotationWrapper = forall a. (Data a) => AnnotationWrapper a toAnnotationWrapper :: (Data a) => a -> AnnotationWrapper toAnnotationWrapper what = AnnotationWrapper what