# Aliases for Union{T, Nothing} and Union{T, Missing}?

**URL:** https://discourse.julialang.org/t/aliases-for-union-t-nothing-and-union-t-missing/15402
**Category:** New to Julia
**Created:** [September 24, 2018, 12:03am UTC](https://discourse.julialang.org/t/aliases-for-union-t-nothing-and-union-t-missing/15402 "2018-09-24T00:03:13Z")
**Posts on this page:** 1
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### Author: ![Tamas\_Papp](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/tamas_papp/32/25949_2.png) [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)
#### Post date: [September 24, 2018, 5:53am UTC](https://discourse.julialang.org/t/aliases-for-union-t-nothing-and-union-t-missing/15402/11 "2018-09-24T05:53:13Z")

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> [@JeffreySarnoff](#):
>
> (until then, you should be good with those three)

I think that _extensions_ don’t break 1.0, so in theory they would be OK.

That said, I prefer `Union{T, Missing}` & similar. I am sure I would have a hard time remembering which of `Maybe`, `Option`, and other variants corresponds to which singleton (as the discussion demonstrates, this is not intuitive at all); just as I don’t remember precedence tables so I try to avoid relying on them.

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