Simon Marlow of Facebook
Simon Marlow is a Software Engineer at Facebook in London. He is a co-author of the Glasgow Haskell Compiler, author of the book “Parallel and Concurrent Programming in Haskell”, and has a string of research publications in functional programming, language design, compilers, and language implementation.
Abstract
Facebook has a large existing system that identifies and remediates abuse: primarily spam, but also other types of abuse, using a combination of techniques including manually written rules and machine learning classifiers. This system actively and automatically prevents vast amounts of undesirable content from reaching users of Facebook.
The system provides a domain-specific language in which the detection logic is written, and we are in the process of migrating this language from an in-house functional language called FXL to Haskell. At the current time, the system is running nearly all of its requests on Haskell. We believe this is the largest Haskell deployment currently in existence.
In this talk I'll explain the problem domain, and why Haskell is uniquely suited to it. The key value proposition of the DSL implementation is implicit concurrency, and I'll outline our solution to this (the Haxl framework). I'll also cover many of the engineering problems we had to solve, including how we deploy new code, going from a source code change to running new code on all the machines in a few minutes. The migration path we are on is littered with the corpses of bugs found and problems solved; I'll share a few of the war stories and the lessons we have learned. The talk is aimed at a general audience, and no specialist knowledge of Haskell is required.