PrettyPrinter

Prettyprinter is a class of software tools and libraries that produce readable, aesthetically pleasing textual representations of structured data and source code. They transform abstract syntax trees, data structures, or code into formatted text that adheres to a consistent style.

Purpose and scope: These tools aim to improve readability, reduce cognitive load, and help maintain consistency across a project. They can operate as language-specific formatters, which know the syntax and idioms of a language, or as general-purpose printers that render generic data structures in a stable form.

Approach and features: Most prettyprinters use a document-oriented design. They parse input into a structural representation, then apply a layout algorithm to choose line breaks and indentation given a width constraint. Configurable options typically include wrap width, indentation size, trailing separators, and style rules. Some also preserve comments and source mappings, or integrate with editors to format on save.

Applications: In programming, prettyprinters are used for source-code formatting, debugging prints of data, and pretty-printing serialized formats like JSON or YAML. They are often separate from compilers, serving as tooling to enforce style guides and readability.

Limitations and notes: A formatter does not change program semantics but may adjust whitespace, comments, and layout in ways that affect readability and editing. Some languages have multiple tools with different style rules, so configuration is common. Overall, the concept underpins a wide range of development workflows aimed at producing clear and consistent text representations.