# How to \`promote\_type\` of more than 2 values?

**URL:** <https://discourse.julialang.org/t/how-to-promote-type-of-more-than-2-values/25088>\
**Category:** General Usage\
**Tags:** type\
**Created:** [June 9, 2019, 4:44am UTC](https://discourse.julialang.org/t/how-to-promote-type-of-more-than-2-values/25088 "2019-06-09T04:44:57Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![singularitti](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/singularitti/32/17678_2.png) [@singularitti](https://discourse.julialang.org/u/singularitti)\
**Post date:** [June 9, 2019, 4:44am UTC](https://discourse.julialang.org/t/how-to-promote-type-of-more-than-2-values/25088/1 "2019-06-09T04:44:57Z")

</div>

For example, I have 4 numbers `1, 2, 3, 4.0`, and I want to get their promoted type. What should I do? I currently have two ways of writing

```julia
julia> promote_type(map(typeof, promote(1, 2, 3, 4.0))...)
Float64

```

or

```julia
julia> eltype(promote(1, 2, 3, 4.0))
Float64

```

Isn’t there a built-in way of doing this?

---

<div class="post-metadata">

**Author:** ![mohamed82008](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/mohamed82008/32/18171_2.png) [@mohamed82008](https://discourse.julialang.org/u/mohamed82008)\
**Post date:** [June 9, 2019, 4:54am UTC](https://discourse.julialang.org/t/how-to-promote-type-of-more-than-2-values/25088/2 "2019-06-09T04:54:22Z")

</div>

` Base.promote_typeof(1, 2.0, 1//2)`

---

<div class="post-metadata">

**Author:** ![singularitti](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/singularitti/32/17678_2.png) [@singularitti](https://discourse.julialang.org/u/singularitti)\
**Post date:** [June 9, 2019, 5:01am UTC](https://discourse.julialang.org/t/how-to-promote-type-of-more-than-2-values/25088/3 "2019-06-09T05:01:08Z")

</div>

Thanks. Not sure why this is not exported. I mean, this is quite useful, isn’t it?

---

<div class="post-metadata">

**Author:** ![mohamed82008](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/mohamed82008/32/18171_2.png) [@mohamed82008](https://discourse.julialang.org/u/mohamed82008)\
**Post date:** [June 9, 2019, 5:12am UTC](https://discourse.julialang.org/t/how-to-promote-type-of-more-than-2-values/25088/4 "2019-06-09T05:12:19Z")

</div>

Not mainstream enough maybe 🤷‍♂️