Wolfgang Jeltsch pushed to branch wip/jeltsch/text-read-uncovering at Glasgow Haskell Compiler / GHC Commits: c3c6efeb by Wolfgang Jeltsch at 2026-04-08T16:28:18+03:00 Move the implementation of `readConstr` into `base` - - - - - 2 changed files: - libraries/base/src/Data/Data.hs - libraries/ghc-internal/src/GHC/Internal/Data/Data.hs Changes: ===================================== libraries/base/src/Data/Data.hs ===================================== @@ -99,3 +99,38 @@ module Data.Data ( import GHC.Internal.Data.Data import Data.Typeable + +import GHC.Real (toRational) +import GHC.Float (Double) +import Data.Eq ((==)) +import Data.Function ((.)) +import Data.Maybe (Maybe (Nothing, Just)) +import Data.List (filter) +import Data.String (String) +import Text.Read (Read, reads) + +-- | Lookup a constructor via a string +readConstr :: DataType -> String -> Maybe Constr +readConstr dt str = + case dataTypeRep dt of + AlgRep cons -> idx cons + IntRep -> mkReadCon (\i -> (mkPrimCon dt str (IntConstr i))) + FloatRep -> mkReadCon ffloat + CharRep -> mkReadCon (\c -> (mkPrimCon dt str (CharConstr c))) + NoRep -> Nothing + where + + -- Read a value and build a constructor + mkReadCon :: Read t => (t -> Constr) -> Maybe Constr + mkReadCon f = case (reads str) of + [(t,"")] -> Just (f t) + _ -> Nothing + + -- Traverse list of algebraic datatype constructors + idx :: [Constr] -> Maybe Constr + idx cons = case filter ((==) str . showConstr) cons of + [] -> Nothing + hd : _ -> Just hd + + ffloat :: Double -> Constr + ffloat = mkPrimCon dt str . FloatConstr . toRational ===================================== libraries/ghc-internal/src/GHC/Internal/Data/Data.hs ===================================== @@ -61,6 +61,7 @@ module GHC.Internal.Data.Data ( mkIntType, mkFloatType, mkCharType, + mkPrimCon, mkNoRepType, -- ** Observers dataTypeName, @@ -94,7 +95,6 @@ module GHC.Internal.Data.Data ( constrIndex, -- ** From strings to constructors and vice versa: all data types showConstr, - readConstr, -- * Convenience functions: take type constructors apart tyconUQname, @@ -126,10 +126,8 @@ import GHC.Internal.Base ( import GHC.Internal.Err (errorWithoutStackTrace) import GHC.Internal.List import GHC.Internal.Num -import GHC.Internal.Read import GHC.Internal.Show import GHC.Internal.Tuple (Solo (..)) -import GHC.Internal.Text.Read( reads ) import GHC.Internal.Types ( Bool(..), Char, Coercible, Float, Double, Type, type (~), type (~~), ) @@ -688,32 +686,6 @@ showConstr :: Constr -> String showConstr = constring --- | Lookup a constructor via a string -readConstr :: DataType -> String -> Maybe Constr -readConstr dt str = - case dataTypeRep dt of - AlgRep cons -> idx cons - IntRep -> mkReadCon (\i -> (mkPrimCon dt str (IntConstr i))) - FloatRep -> mkReadCon ffloat - CharRep -> mkReadCon (\c -> (mkPrimCon dt str (CharConstr c))) - NoRep -> Nothing - where - - -- Read a value and build a constructor - mkReadCon :: Read t => (t -> Constr) -> Maybe Constr - mkReadCon f = case (reads str) of - [(t,"")] -> Just (f t) - _ -> Nothing - - -- Traverse list of algebraic datatype constructors - idx :: [Constr] -> Maybe Constr - idx cons = case filter ((==) str . showConstr) cons of - [] -> Nothing - hd : _ -> Just hd - - ffloat :: Double -> Constr - ffloat = mkPrimCon dt str . FloatConstr . toRational - ------------------------------------------------------------------------------ -- -- Convenience functions: algebraic data types View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/c3c6efeb13ec864068bc5b5b60a9d378... -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/c3c6efeb13ec864068bc5b5b60a9d378... You're receiving this email because of your account on gitlab.haskell.org.