If I use integer-simple there is a completely different definition of Natural. 

How I construct now naturalTyCon (to make `naturalTy` to use it instead of `typeNatKind`) : 

```naturalTyCon :: TyCon
naturalTyCon = pcTyCon naturalTyConName Nothing [] [natSDataCon,natJDataCon]

natSDataCon :: DataCon
natSDataCon = pcDataCon natSDataConName [] [wordPrimTy] naturalTyCon

etc... 

```

Now I have to check`DynFlags` in a few places to reimplement `naturalTyCon` in case of using `integer-simple`. 

Is there a way to avoid hardcoding of `naturalTy`? 

My colleague said that it would be nice to get `naturalTy` from an environment by  something like `lookupTyCon`, 

but there are many functions whose don't use any environment like functions from `typeNatTyCons` list in `GHC.Builtin.Types.Literals`. 

Now I am going to use `DynFlags` checking, but it looks like an ugly way... 

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