Functional Programming in Scala, Second Edition

9 Parser combinators

This chapter covers

• Introducing parser combinators
• Designing and using APIs without implementations

In this chapter, we’ll work through the design of a combinator library for creating parsers. We’ll use JSON parsing (http://mng.bz/DpNA) as a motivating use case. Like chapters 7 and 8, this chapter is not so much about parsing as it is about providing further insight into the process of functional design.

What is a parser?

A parser is a specialized program that takes unstructured data (e.g., text or any kind of stream of symbols, numbers, or tokens) as input, and outputs a structured representation of that data. For example, we can write a parser to turn a comma-separated file into a list of lists, where the elements of ...