RealWorld -package:proto-lens is:exact

data RealWorld
base Control.Monad.ST Control.Monad.ST.Lazy Control.Monad.ST.Lazy.Safe Control.Monad.ST.Safe GHC.Base GHC.Exts, ghc-prim GHC.Prim, primitive Control.Monad.Primitive, foldl Control.Foldl, ihaskell IHaskellPrelude, massiv Data.Massiv.Array.Mutable, parameterized-utils Data.Parameterized.HashTable, ghc-internal GHC.Internal.Base GHC.Internal.Control.Monad.ST GHC.Internal.Control.Monad.ST.Imp GHC.Internal.Control.Monad.ST.Lazy GHC.Internal.Control.Monad.ST.Lazy.Imp GHC.Internal.Exts, what4 What4.Utils.MonadST, rebase Rebase.Prelude, massiv-test Test.Massiv.Utils
RealWorld is deeply magical. It is primitive, but it is not unlifted (hence ptrArg). We never manipulate values of type RealWorld; it's only used in the type system, to parameterise State#.
data RealWorld
base-prelude BasePrelude, mutable-containers Data.Mutable, stateref Data.StateRef.Instances, prim-uniq Data.Unique.Prim Data.Unique.Tag, pvar Data.Primitive.PVar, declarative Numeric.MCMC
RealWorld is deeply magical. It is primitive, but it is not unlifted (hence ptrArg). We never manipulate values of type RealWorld; it's only used in the type system, to parameterise State#.
data RealWorld
open-witness Data.OpenWitness Data.OpenWitness.ST
The s type for running OW in IO.