# Why \`Tuple{Vararg{T, 2} where T} == Tuple{Any, Any}\`?
**URL:** https://discourse.julialang.org/t/why-tuple-vararg-t-2-where-t-tuple-any-any/33511
**Category:** General Usage
**Created:** [January 18, 2020, 5:16am UTC](https://discourse.julialang.org/t/why-tuple-vararg-t-2-where-t-tuple-any-any/33511 "2020-01-18T05:16:05Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@Wenjie](https://discourse.julialang.org/u/Wenjie)
#### Post date: [January 18, 2020, 5:16am UTC](https://discourse.julialang.org/t/why-tuple-vararg-t-2-where-t-tuple-any-any/33511/1 "2020-01-18T05:16:05Z")
Why this is the case, instead of being a `UnionAll` like Arrays?
---
### Author:  [@bkamins](https://discourse.julialang.org/u/bkamins)
#### Post date: [January 18, 2020, 10:08am UTC](https://discourse.julialang.org/t/why-tuple-vararg-t-2-where-t-tuple-any-any/33511/2 "2020-01-18T10:08:30Z")
Tuples are covariant as opposed to all other parametric types that are invariant.
The reason for this is that tuples are used in signature matching in method dispatch, see [https://docs.julialang.org/en/latest/manual/types/#Tuple-Types-1](https://docs.julialang.org/en/latest/manual/types/#Tuple-Types-1).
Here is an example of this distinction:
```julia
julia> Tuple{Int} <: Tuple{Any}
true
julia> Vector{Int} <: Vector{Any}
false
julia> Vector{Int} <: Vector{<:Any}
true
```
You might also check out an answer on [StackOverflow](https://stackoverflow.com/questions/59798109/why-union-type-not-accepting-one-of-its-types-in-julia) that I have just written on a related topic.
---
### Author:  [@Wenjie](https://discourse.julialang.org/u/Wenjie)
#### Post date: [January 21, 2020, 1:39am UTC](https://discourse.julialang.org/t/why-tuple-vararg-t-2-where-t-tuple-any-any/33511/3 "2020-01-21T01:39:20Z")
I was thinking in the same direction too. I managed to convince myself after testing:
```julia
Union{Tuple{Int}, {Tuple{Any}} == Tuple{Any}
```