Source Code Without Implicitness: Explicit Source Prose For Programming Education

The meaning of source code is captured in the syntax of a programming language. To understand a particular code fragment one must thus know the mapping of the used syntactic constructs to their meaning. Novices often lack this knowledge. To make up for this, they often resort to guessing, which leads to misunderstandings in this mapping that may be hard to unlearn. In this paper we present a didactic tool called Explicit Source Prose: source code written in what we call an Explicit Syntax. An explicit syntax makes the precise semantics it represents explicit in structured natural language. We discuss different aspects of Explicit Source Prose: it does not explain purpose, it is localizable, explicitness is a spectrum, it can be generated automatically, and it reveals typos that alter a program’s meaning. We illustrate the concept of Explicit Source Prose with examples of source code and corresponding source prose. Preliminary results of a study with ten participants indicate that novices appreciate Explicit Source Prose and that they are able to more easily understand source code when an Explicit Source Prose version is available.