I’ve ran into a type membership question with Type{T}, which seems to be behaving counterintuitively. According to the documentation, Type{T} is the singleton consisting of the type T itself. Thus, isa(Int, Type{T}) returns true. However, if we combine this with a tuple, the relationship breaks dow…

Ah, I solved my problem, though it’s not a general solution to Type{T} oddness. In my particular case, I realized that arg_type_tuple isn’t equivalent to typeof in the case of Type arguments, so I can just duplicate that functionality and get semantically equivalent dispatch.

Membership of Type{T}

Internals & Design

Tamas_Papp April 15, 2020, 5:38pm 2

It is very likely that you are looking for

julia> isa(Tuple{Int}, Type{Tuple{Int}})
true

I would recommend thinking of Type{T} as sugar for dispatching on a type value T, not as part of the type hierarchy. See