# New abstract supertype of existing type

**URL:** <https://discourse.julialang.org/t/new-abstract-supertype-of-existing-type/63624>\
**Category:** General Usage\
**Tags:** type\
**Created:** [June 27, 2021, 2:16am UTC](https://discourse.julialang.org/t/new-abstract-supertype-of-existing-type/63624 "2021-06-27T02:16:03Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Joris\_Pinkse](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/joris_pinkse/32/216398_2.png) [@Joris\_Pinkse](https://discourse.julialang.org/u/Joris_Pinkse)\
**Post date:** [June 27, 2021, 2:16am UTC](https://discourse.julialang.org/t/new-abstract-supertype-of-existing-type/63624/1 "2021-06-27T02:16:03Z")

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1. Can a type have more than one immediate supertype? If not, why not?

2. If it can, then can one define an abstract supertype of e.g. Float64? [I sense from [Make an existing type a child of an abstract type - #2 by Raf](https://discourse.julialang.org/t/make-an-existing-type-a-child-of-an-abstract-type/28162/2) and [How to make an abstract type as a super type of composite types](https://discourse.julialang.org/t/how-to-make-an-abstract-type-as-a-super-type-of-composite-types/27174) that the answer is (still?) no, and I suspect that someone will advise me that this would be a very bad idea and (hopefully also) why]

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**Author:** ![jzr](https://avatars.discourse-cdn.com/v4/letter/j/eb9ed0/32.png) [@jzr](https://discourse.julialang.org/u/jzr)\
**Post date:** [June 27, 2021, 2:22am UTC](https://discourse.julialang.org/t/new-abstract-supertype-of-existing-type/63624/2 "2021-06-27T02:22:39Z")

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No it can’t.

[https://github.com/JuliaLang/julia/issues/5](https://github.com/JuliaLang/julia/issues/5)