# Syntax idea: \`\[1 M\]\` to accomplish \`hcat( ones(size(M,1)), M )\` by broadcasting

**URL:** https://discourse.julialang.org/t/syntax-idea-1-m-to-accomplish-hcat-ones-size-m-1-m-by-broadcasting/251
**Category:** Internals & Design
**Tags:** broadcast
**Created:** [November 11, 2016, 2:30pm UTC](https://discourse.julialang.org/t/syntax-idea-1-m-to-accomplish-hcat-ones-size-m-1-m-by-broadcasting/251 "2016-11-11T14:30:33Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![pitao](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/pitao/32/116_2.png) [@pitao](https://discourse.julialang.org/u/pitao)
#### Post date: [November 11, 2016, 2:30pm UTC](https://discourse.julialang.org/t/syntax-idea-1-m-to-accomplish-hcat-ones-size-m-1-m-by-broadcasting/251/1 "2016-11-11T14:30:33Z")

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If you saw

```julia
[1 M]

```

What would you expect?

I would expect a new column of `1`s to be prepended to matrix `M`. i.e. the `1` would be broadcast.

So it would accomplish:

```julia
hcat( ones(size(M,1)), M )

```

Similarly `[1;M]` would `vcat`

What think ye, O creators?

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<div class="post-metadata">

### Author: ![stevengj](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/stevengj/32/71_2.png) [@stevengj](https://discourse.julialang.org/u/stevengj)
#### Post date: [November 11, 2016, 3:26pm UTC](https://discourse.julialang.org/t/syntax-idea-1-m-to-accomplish-hcat-ones-size-m-1-m-by-broadcasting/251/2 "2016-11-11T15:26:20Z")

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You could also intend for `1` to be the identity matrix, or to get a unit vector. Because the results aren’t clear, it seems better to throw an error and force the user to be explicit.