Sentence is about Complex type but mentions Simple constructor
There is a mistype in one of the sentences regarding Roles in the documentation : https://ghc.readthedocs.io/en/latest/glasgow_exts.html\#nominal-representational-and-phantom
Here are some examples: data Simple a = MkSimple a -- a has role representational type family F type instance F Int = Bool type instance F Age = Char data Complex a = MkComplex (F a) -- a has role nominal data Phant a = MkPhant Bool -- a has role phantom
The type Simple has its parameter at role representational, which is generally the most common case. Simple Age would have the same representation as Simple Int. The type Complex, on the other hand, has its parameter at role nominal, because Simple Age and Simple Int are not the same. Lastly, Phant Age and Phant Bool have the same representation, even though Age and Bool are unrelated.
The wrong sentence is
The type Complex, on the other hand, has its parameter at role nominal, because Simple Age and Simple Int are not the same.