# Why does Julia not support multiple traits?

**URL:** <https://discourse.julialang.org/t/why-does-julia-not-support-multiple-traits/5278>\
**Category:** Internals & Design\
**Tags:** traits\
**Created:** [August 8, 2017, 11:36am UTC](https://discourse.julialang.org/t/why-does-julia-not-support-multiple-traits/5278 "2017-08-08T11:36:07Z")\
**Posts on this page:** 1\
**Showing post:** 44

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**Author:** ![StefanKarpinski](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/stefankarpinski/32/24_2.png) [@StefanKarpinski](https://discourse.julialang.org/u/StefanKarpinski)\
**Post date:** [August 14, 2017, 2:41pm UTC](https://discourse.julialang.org/t/why-does-julia-not-support-multiple-traits/5278/44 "2017-08-14T14:41:49Z")

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I don’t really think a design is required for this – it’s pretty well understood. Multiple inheritance where you can add ancestors to types after-the-fact is what I described in [issue #5](https://github.com/JuliaLang/julia/issues/5) (the oldest open issue). This is the maximally powerful design. It is also the hardest design to implement, and makes #265 look like child’s play compared to the kinds of updates you might need to do in order to keep the world coherent. Sometimes it’s a good idea to give people a lot of power in a language feature, but other times it’s better to restrict the power you give them. It’s still unclear which situation this is.

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