Historical how and why of hash tables

Length: 35 minutes

Prerequisites: Basic familiarity with associative data structures (hashes, dictionaries, associative arrays) in some language

Description

Hash tables, dictionaries, and other associative data structures are so ubiquitous in modern programming languages that we can forget that at one time they were fresh and innovative. How did we live without them? Not too well, as I will describe.

I will explain how hashes work in general and compare the implementations in the Perl and Python programming languages. I'll also discuss the non-hash implementation of similar language features in the earlier languages Lisp (1960ish) and SNOBOL (1965ish).

This talk will be suitable for:

• people who have never heard of a hash table
• people who know what it is but not how it works
• people who know how it works but are interested in history

Start here

Browse the slides

Lecture notes: what I said in the talk

Complete slides, tgz file

Complete slides, zip file

Video

Thanks to Chris Ball, a video of this talk is available.

Older Versions

The current version is 1.2, which I delivered to Philadelphia Linux Users’ Group in January 2016. It has minor revisions from version 1.0 (April 2015 Recurse Center version) and version 1.1 (July 2015 Perl Mongers version).

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