Why obsessed with NumPy interface? First of all, NumPy is an extension to the Python programming language, with support for large, multi-dimensional arrays, matrices, and a large library of high-level mathematical functions to operate on these abstractions. If you just begin to learn deep learning, you should absolutely start from NumPy to gain a firm grasp of its concepts (see, for example, the Stanford's CS231n course). For quick prototyping of advanced deep learning algorithms, you may often start composing with NumPy as well.Second, as an extension of Python, your implementation follows the intuitive imperative style. This is the only style, and there is no new syntax constructs to learn. To have a taste of this, let's look at some examples below.