Implementing Doubly Linked Lists in Haskell

New York Haskell Users Group, November 13, 2014
Implementing Doubly Linked Lists in Haskell by Brian Hurt
Haskell poses several unique problems in implementing the standard doubly linked list data structure. I show the major problems Haskell has, and explain not one, but two different solutions to the problem (for those who already know the answer, yes it's deques I'm talking about). Basic knowledge of Haskell (simple type classes, variant types and pattern matching) is assumed, as well as some familiarity with doubly linked lists in other languages.
Brian Hurt has been a professional software engineer for 20 years now (quite a feat for someone who still claims to be 29 years old), originally in device drivers and embedded work, but more recently in functional programming languages and databases. He has been paid to program in OCaml, Clojure, and assembly language, as well as a number of other programming languages (including Java, C++, and C). To his dismay, he doesn't have any professional Haskell experience, but has been learning it for the past several years. He is currently working at kloud.co, which is a still stealth-mode start up (although they're hoping to change that soon).