{-# OPTIONS_GHC -fno-warn-redundant-constraints #-} {-# LANGUAGE TypeFamilies, MultiParamTypeClasses, FlexibleContexts #-} module Simple24 where import Data.Kind (Type) linear :: HasTrie (Basis v) => (Basis v, v) linear = basisValue class HasTrie a where type family Basis u :: Type basisValue :: (Basis v,v) basisValue = error "urk"