{-# LANGUAGE UndecidableInstances #-} -- required below GHC 9.6 module Generic.Data.Function.FoldMap.NonSum where import GHC.Generics import Generic.Data.Function.FoldMap.Constructor ( GFoldMapC(gFoldMapC) ) import Generic.Data.Rep.Error {- | 'foldMap' over generic product data types. Take a generic representation, map each field in the data type to a 'Monoid', and combine the results with ('<>'). -} class GFoldMapNonSum m f where gFoldMapNonSum :: f p -> m instance GFoldMapC m f => GFoldMapNonSum m (C1 c f) where gFoldMapNonSum (M1 a) = gFoldMapC a instance GFoldMapNonSum m (l :+: r) where gFoldMapNonSum = error eNoSum instance GFoldMapNonSum m V1 where gFoldMapNonSum = error eNoEmpty