REPL output for subtype of Function

[dlfivefifty]

How is one meant I override the default output in the REPL? This early thread Proper way to hook into REPL display of type seems to suggest using show, but this doesn’t work for subtypes of Function:

julia> struct Foo <: Function end

julia> Base.show(io::IO,::Foo) = print(io, "hello")

julia> Foo()
(::Foo) (generic function with 0 methods)

julia> show(Foo())
hello

[kristoffer.carlsson]

julia> struct Foo <: Function end

julia> Base.show(io::IO, ::MIME"text/plain", ::Foo) = print(io, "Hello")

julia> Foo()
Hello

Show for supertype

I am trying to organize printing for a set of types the following way: a generic function returns a string representation, then show for the supertype just prints it. MWE: abstract type MyAbstractFun <: Function end Base.show(io::IO, f::MyAbstractFun) = println(io, representation(f)) struct One <: MyAbstractFun end (::One)(x) = x+1 representation(::One) = "just adds one" but then evaluating at the REPL (ie going through display) gives me the standard printing from Base, while show works correc…