Introduction

    - Why purely functional data-structures?
        - easier to reason about
        - higher-level features: Undo
        - concurrency
        - memory sharing
        - case study: Git
    - Survey of existing work (Okasaki, etc.)
    - Aim of book 
        - to provide a grounding to Purely Functional data-structures 
        - for the working programmer (not for CompSci audience)
        - with examples in Modern Perl