T15954.hs:10:1: error:
    • The type synonym ‘A’ should have 1 argument, but has been given none
    • In the type synonym declaration for ‘C1’

T15954.hs:14:1: error:
    • The type synonym ‘A’ should have 1 argument, but has been given none
    • In the type synonym declaration for ‘C2’