There are enough existing examples that in practice it's easy enough to find a workaround, but having a direct equivalent would reduce friction. Is there a reason this was not included in mix-swift?

It wasn't added because there is an idiomatic swift way of doing it (since Range and friends implement Collection):

let a = MLXArray(0 ..< 12)

There are range variants for open, closed and strides -- all of the arange calls can be expressed with these.

Do you think arange gives something compelling over these?

The main motivation would be discoverability, especially since models are now commonly ported with automated tools. This came to mind as I was cleaning up the mlx-audio repo, which contained some workarounds for arange in Swift.

Perhaps there's also a performance benefit of using the MLX C API directly, which uses lazy computation?

The syntax with step is also more concise:

// Current workarounds
let a = MLXArray(stride(from: 0, to: 12, by: 2))
let b = MLXArray(stride(from: 0.0, to: 5.0, by: 0.5))

let a = MLXArray.arange(0, 12, step: 2)
let b = MLXArray.arange(0.0, 5.0, step: 0.5)

That seems reasonable -- we can cross link the documentation between the two styles. Using mlx_arange may actually be a performance gain as it will probably initialize the array on the GPU.

Agreed; we did a bit of workaround for mlx-audio swift port

@DePasqualeOrg looks like a swift-format failure.

Sorry about that. I ran the formatting again.