# Why are tuples covariant?
**URL:** https://discourse.julialang.org/t/why-are-tuples-covariant/45005
**Category:** Internals & Design
**Tags:** type, tuple, parametric-types
**Created:** [August 15, 2020, 5:45pm UTC](https://discourse.julialang.org/t/why-are-tuples-covariant/45005 "2020-08-15T17:45:58Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@OliverEvans96](https://discourse.julialang.org/u/OliverEvans96)
#### Post date: [August 15, 2020, 5:45pm UTC](https://discourse.julialang.org/t/why-are-tuples-covariant/45005/1 "2020-08-15T17:45:58Z")
The manual section on [Parametric Types](https://docs.julialang.org/en/v1/manual/types/#Parametric-Types-1) says that
> Julia’s type parameters are _invariant_
but the section on [Tuple Types](https://docs.julialang.org/en/v1/manual/types/#Tuple-Types-1) says
> Tuple types are _covariant_ in their parameters
I’m just curious about the reason behind this design choice. It seems a bit confusing to me as a Julia novice, but I’m sure somebody much more knowledgeable than I had a good reason to design it this way.
Thanks,
Oliver
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### Author:  [@Oscar\_Smith](https://discourse.julialang.org/u/Oscar_Smith)
#### Post date: [August 15, 2020, 6:07pm UTC](https://discourse.julialang.org/t/why-are-tuples-covariant/45005/2 "2020-08-15T18:07:16Z")
The reason here is mainly historical. There actually is a proposal to change it for Julia 2.0 [https://github.com/JuliaLang/julia/issues/24614](https://github.com/JuliaLang/julia/issues/24614)
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### Author:  [@Raf](https://discourse.julialang.org/u/Raf)
#### Post date: [August 15, 2020, 6:17pm UTC](https://discourse.julialang.org/t/why-are-tuples-covariant/45005/3 "2020-08-15T18:17:14Z")
Also dispatching on Tuples is useful and it’s easier with covariance, especially `Vararg`.