Paper of the Week: Out of the Tar Pit

David albert circle David Albert

This is part of our “Paper of the Week” series. For more info, check out our introductory blog post.

This week’s paper is Out of the Tar Pit by Ben Moseley and Peter Marks, which was presented at SPA2006.

Out of the Tar Pit was submitted by Hacker Schooler Pablo Torres, who shared the following:

In Out of the Tar Pit, Moseley and Marks argue that the biggest source of complexity in programs is mutable state, because keeping track of all possible combinations of bits is unmanageable. They introduce the notions of essential and incidental complexity, the former referring to details that are inherent to a problem and the latter to those complications that arise due to a particular solution one might attempt - for example, issues added by the programming language in use.

They continue by comparing Object-Oriented Programming’s approach of breaking state up into small, manageable pieces and providing controlled mutations with Functional Programming’s solution of avoiding mutations altogether; they also spend some time analyzing Logic Programming. They favor the simplicity of FP, even though they admit that it takes discipline to achieve.

Finally, they offer recommendations on how to build systems that are easy to reason about by using the tools provided by Functional Programming and relational database modelling.

Here’s the abstract from the paper:

Complexity is the single major difficulty in the successful development of large-scale software systems. Following Brooks we distinguish accidental from essential difficulty, but disagree with his premise that most complexity remaining in contemporary systems is essential. We identify common causes of complexity and discuss general approaches which can be taken to eliminate them where they are accidental in nature. To make things more concrete we then give an outline for a potential complexity-minimizing approach based on functional programming and Codd’s relational model of data.

Read Along

Read Along is a way for you to participate in Paper of the Week. If you want to take part, all you have to do is read the paper, make something small in response (code or prose), and email us a link of what you make by noon Eastern Time next Monday.

Last week’s paper was The Chubby Lock Service for Loosely-Coupled Distributed Systems. Here are the Read Along submissions:

Happy reading!