Functions are abstractions in time; data structures are abstractions in space. For example, the same abstraction looks like binary search when drscribed as a function and it looks like a binary tree when described as a data structure. What binary search looks like by itself is unthinkable to us because anything we can think about has to be projected to space or time.

Edit. If the vertical axis is time and the horizontal plane is space, then the floating something in the middle is the 'abstraction', its shadow on the plane below is its data structure and its projection onto the vertical axis is its function. The need to compress everything into the 1-dimensional time is what creates those for-loops and ifs. The art of finding the right data structure is the art of finding the right angle at which the 'abstraction' drops a good descriptive shadow.