# Union of missing and number
**URL:** https://discourse.julialang.org/t/union-of-missing-and-number/13834
**Category:** General Usage
**Created:** [August 21, 2018, 2:27pm UTC](https://discourse.julialang.org/t/union-of-missing-and-number/13834 "2018-08-21T14:27:16Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@tlienart](https://discourse.julialang.org/u/tlienart)
#### Post date: [August 21, 2018, 2:27pm UTC](https://discourse.julialang.org/t/union-of-missing-and-number/13834/1 "2018-08-21T14:27:16Z")
This is related to a SO question ([here](https://stackoverflow.com/questions/51950256/julia-creating-a-method-for-any-vector-with-missing-values/51950470?noredirect=1#comment90851114_51950470)):
Why does this work:
```julia
foo(x::Vector{Union{Missing, T}}) where T<:Number = sum(collect(skipmissing(x)))
foo([1, 2, missing])
>> 3
```
but not this
```julia
bar(x::Vector{Union{Missing, <:Number}}) = sum(collect(skipmissing(x)))
bar([1, 2, missing])
```
```julia
ERROR: MethodError: no method matching bar(::Array{Union{Missing, Int64},1})
Closest candidates are:
bar(::Array{Union{Missing, #s1} where #s1<:Number,1}) at REPL[58]:1
Stacktrace:
[1] top-level scope at none:0
```
---
### Author:  [@kristoffer.carlsson](https://discourse.julialang.org/u/kristoffer.carlsson)
#### Post date: [August 21, 2018, 2:28pm UTC](https://discourse.julialang.org/t/union-of-missing-and-number/13834/2 "2018-08-21T14:28:54Z")
The `where` is in a different “scope”.
```julia
foo(x::Vector{Union{Missing, T}}) where T<:Number
# vs
foo(x::Vector{Union{Missing, T} where T<:Number})
```
---
### Author:  [@tlienart](https://discourse.julialang.org/u/tlienart)
#### Post date: [August 21, 2018, 2:30pm UTC](https://discourse.julialang.org/t/union-of-missing-and-number/13834/3 "2018-08-21T14:30:47Z")
That makes sense, it seems to me it’s the kind of slightly tricky thing that may benefit from being in the doc, do you know if there’s something about such “scopes”? thanks!