That is amazing. My main doubt would be how future proof this is. Does it wrap numpy? Or something equivalent? Does it require continuous development to keep up?

Also I both understand the need for declaring the matrices up front and think it's a bit of a shame that it is not seamless.

Here are some (ill-advised?) alternatives:

    X, Y, Z = dp.Slots()
    
    with dp.Slot() as X:
        ...
    
    import dp.Slot as new
    X = new['i','j'] = ...

    X = dp['i','j'] = ...