Much happier with the type errors today than yesterday. Here, the type checker was able to determine that a property is not Debian-specific like but will work on other unix's too:

src/Propellor/Property/Git.hs:158:9:
    Couldn't match type ‘'[]’ with ‘'['Targeting 'OSFreeBSD]’
    Expected type: UncheckedProperty DebianLike
      Actual type: UncheckedProperty UnixLike
    In the first argument of ‘changesFileContent’