Parser combinators in Scala

Parser combinators are well-known in functional programming languages such as Haskell. In this paper, we describe how they are implemented as a library in Scala, a functional object-oriented language. Thanks to Scala's flexible syntax, we are able to closely approximate the EBNF notation supported by dedicated parser generators. For the uninitiated, we first explain the concept of parser combinators by developing a minimal library from scratch. We then turn to a detailed description of the existing Scala library, including its support for denoting variable binding as part of the syntax. We provide several realistic examples to illustrate the utility of our library.