Parser combinators - functions to assemble big parsers from little ones - are an instructive example of composability and reuse made possible through FP, and building one is a useful (and common!) exercise for learners seeking through practical application a solid understanding of abstractions such as applicative functors and monads.

In this talk, we will briefly examine some parsing libraries available for Haskell and discuss their relative benefits and drawbacks. Then we will ignore everything we just saw and build a parser combinator library from scratch. Moreover, our parser will be abstracted over the "whole" and "element" input types - a more general result than most parsers.

I will conclude with a summary of some topics for further study including important parser design decisions, optimisations and efforts to unify parsing and pretty printing.