This way, no import cycles are created (for example with Integer.Morph.decimal and Decimal.truncate) while safe internals are still exposed.
It also creates nice consistency between for example Stack and Stack.Morph,
Stack being in a separate, independent package and Stack.Morph being what elm-morph builds on top.
Maybe the types like Decimal and helpers will one day be in their own library, too and only the Morphs will stay here.