expanding type synonyms in error messages

Hi all, While working with complex types with lots of arguments etc. errors are becoming annoying very fast. For example, GHC prints errors in this way: Expected type: <type without any synonyms> Actual type: <type with synonyms> Now I have to expand that synonym in my head to understand the error. I was wondering if implementing something like this is possible: In type error messages, GHC also prints types that are cleaned from type synonyms. Maybe something like this: Expected type: <type1> (without synonyms): Actual type: <type2> (without synonyms): If this is not always desirable for some reason, we can hide this behavior behind a flag. What do GHC devs think about this? Is this, in theory, possible to do? How hard would it be to implement this? Thanks.