# Lacking documentation about non-types as type parameters

**URL:** https://discourse.julialang.org/t/lacking-documentation-about-non-types-as-type-parameters/83893
**Category:** Internals & Design
**Tags:** question, documentation
**Created:** [July 7, 2022, 1:31pm UTC](https://discourse.julialang.org/t/lacking-documentation-about-non-types-as-type-parameters/83893 "2022-07-07T13:31:24Z")
**Posts on this page:** 1
**Page:** 1

<div class="post-metadata">

### Author: ![yakir12](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/yakir12/32/297_2.png) [@yakir12](https://discourse.julialang.org/u/yakir12)
#### Post date: [July 7, 2022, 1:31pm UTC](https://discourse.julialang.org/t/lacking-documentation-about-non-types-as-type-parameters/83893/1 "2022-07-07T13:31:24Z")

</div>

Type parameters can be non-types that are `isbits` (see 3rd bullet point in [Types · The Julia Language](https://docs.julialang.org/en/v1/manual/types/#man-types)):

```julia
julia> struct A{T} end

julia> A{1.2}
A{1.2}

julia> A{'a'}
A{'a'}

julia> A{π}
A{π}

julia> A{1//2}
A{1//2}

julia> A{1}
A{1}

```

While this is useful for things like `StaticArrays` and more, it hardly gets mentioned in the documentation (with the exception of that 3rd bullet point). There is an issue about applying constraint on said non-type-parameters [here](https://github.com/JuliaLang/julia/issues/9580), but I’d argue that this should receive more attention in the documentation itself.

I might be wrong however.

What do you think?