Export Multiplicities from GHC.Exts
FUN, which takes a argument of kind
Multiplicity. But to actually write out its kind or supply and argument of kind
Multiplicity, one needs to import GHC.Prim.
Multiplicity kind and it's
One constructors are explicitly part of the linear types proposal, they appear to be a user-facing design choice, rather than an implementation detail. Hence I propose exporting them from GHC.Exts as well.