Structured programming is a technique introduced in the mid-1960s to simplify code development, testing, and maintenance. Prior to structured programming, software was written in large monolithic tomes replete with APIs and “go-to” statements. The resultant product might consist of millions of lines of code with thousands of such APIs and go-to statements that were difficult to develop, understand, debug, and maintain.

The essential idea of structured programming was to break the code into a relatively simple “main routine” and then use something called an application programming interface (API) to call subroutines that were designed to be modular and reusable. Example subroutines might provide services like complete a ballistics calculation, or a fast Fourier transform, a linear regression, an average, a sum, or a mean. Structured programming remains the state of the art for many applications today, and has dramatically simplified the process of developing and maintaining computer code.

While this technique is appropriate for many classes of applications, it breaks down with the complexity and scale of the requirements for a modern AI or IoT application, resulting in a Gordian knot depicted in Figure 4.