# \`where T\` vs \`where {T}\`

**URL:** <https://discourse.julialang.org/t/where-t-vs-where-t/16296>\
**Category:** General Usage\
**Created:** [October 13, 2018, 10:59pm UTC](https://discourse.julialang.org/t/where-t-vs-where-t/16296 "2018-10-13T22:59:02Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![pochoi](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/pochoi/32/3742_2.png) [@pochoi](https://discourse.julialang.org/u/pochoi)\
**Post date:** [October 13, 2018, 10:59pm UTC](https://discourse.julialang.org/t/where-t-vs-where-t/16296/1 "2018-10-13T22:59:02Z")

</div>

When I read Julia source codes, sometimes the type parameterization writes `where T`, sometimes `where {T}`. Are they different or the same?

---

<div class="post-metadata">

**Author:** ![foobar\_lv2](https://avatars.discourse-cdn.com/v4/letter/f/ee59a6/32.png) [@foobar\_lv2](https://discourse.julialang.org/u/foobar_lv2)\
**Post date:** [October 13, 2018, 11:11pm UTC](https://discourse.julialang.org/t/where-t-vs-where-t/16296/2 "2018-10-13T23:11:34Z")

</div>

They are the same. `where {T1, T2, T3}` is the same as `where T3 where T2 where T1` is the same as `where {T3} where {T2} where {T1}`.

Some people, me included, prefer to always put in the brackets even if unneeded, in order to aid the eye at scanning for type parameters. But that is a matter of taste. There probably is some piece of history here that I don’t know.

---

<div class="post-metadata">

**Author:** ![JeffreySarnoff](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/jeffreysarnoff/32/1980_2.png) [@JeffreySarnoff](https://discourse.julialang.org/u/JeffreySarnoff)\
**Post date:** [October 14, 2018, 3:14am UTC](https://discourse.julialang.org/t/where-t-vs-where-t/16296/3 "2018-10-14T03:14:10Z")

</div>

not much history beyond the “discovery” that writing  
`where {T1, T2, T3}` leads to nicer visuals than `where T3 where T2 where T1`  
there are occasions when the long form is helpful, where one or more of the Ti are compound or triangular locally