# SomeType{T} where T:\>SomeOtherType

**URL:** https://discourse.julialang.org/t/sometype-t-where-t-someothertype/7815
**Category:** General Usage
**Tags:** parametric-types
**Created:** [December 17, 2017, 2:36pm UTC](https://discourse.julialang.org/t/sometype-t-where-t-someothertype/7815 "2017-12-17T14:36:35Z")
**Posts on this page:** 4
**Page:** 1

<div class="post-metadata">

### Author: ![Bernard\_GODARD](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/bernard_godard/32/4155_2.png) [@Bernard\_GODARD](https://discourse.julialang.org/u/Bernard_GODARD)
#### Post date: [December 17, 2017, 2:36pm UTC](https://discourse.julialang.org/t/sometype-t-where-t-someothertype/7815/1 "2017-12-17T14:36:35Z")

</div>

Is there good documentation about what this means:

```julia
SomeType{T} where T:>SomeOtherType

```

and more generally:

```julia
SomeType{T} where SomeOtherType<:T<:YetAnotherype

```

I get this strange? result:

```julia
julia> Vector{Number}<:Vector{T} where String<:T<:Number
true

```

but String is not a subtype of Number.  
and I would expect this type to be the empty set.

Thank you,

---

<div class="post-metadata">

### 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: [December 17, 2017, 2:52pm UTC](https://discourse.julialang.org/t/sometype-t-where-t-someothertype/7815/2 "2017-12-17T14:52:47Z")

</div>

Documentation is [in the manual](https://docs.julialang.org/en/latest/manual/types/#UnionAll-Types-1).

I am also surprised by what you get, since

```julia
julia> Vector{Number} <: (Vector{T} where T >: String)
false

```

(also, please [use backticks to quote code)](https://discourse.julialang.org/t/psa-how-to-quote-code-with-backticks/7530)

---

<div class="post-metadata">

### 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: [December 17, 2017, 2:56pm UTC](https://discourse.julialang.org/t/sometype-t-where-t-someothertype/7815/3 "2017-12-17T14:56:45Z")

</div>

This may be related:  
[https://github.com/JuliaLang/julia/issues/24179](https://github.com/JuliaLang/julia/issues/24179)

---

<div class="post-metadata">

### Author: ![Bernard\_GODARD](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/bernard_godard/32/4155_2.png) [@Bernard\_GODARD](https://discourse.julialang.org/u/Bernard_GODARD)
#### Post date: [December 18, 2017, 10:17am UTC](https://discourse.julialang.org/t/sometype-t-where-t-someothertype/7815/4 "2017-12-18T10:17:16Z")

</div>

Thank you @Tamas_Papp  
This is the same problem.

I have edited my post to quote code properly.