Jake Zimmerman

Hey there! Here are some links you might be interested in:

If you want to contact me, I prefer email or, Signal. I infrequently check Twitter and Mastodon.
However, please avoid DM’ing me to ask questions about Sorbet.

Projects
Writing
Talks
Work
Other interests

Projects

Why is programming fun? What delights may its practitioner expect as his reward?

Fred Brooks, The Mythical Man-Month

I keep all the things I spend my time working on on GitHub.
Here are my favorite kinds of things to work on:

Command line utilities

I mostly write command line tools in Bash and Haskell.
Tools for writing

I use Pandoc and Markdown for all my writing needs.
Vim plugins

I’m a big fan of Vim. In fact, this page is designed to look like what syntax-highlighted markdown looks like when I open Vim.
My dotfiles

I spend a lot of time configuring my development environment.
Programming language theory

I’ve been fascinated by types and programming languages since school, and enjoy putting the ideas I’ve learned into practice.

Writing

With writing you have the extraordinary power of a Turing machine.

Manuel Blum, Advice to a Beginning Graduate Student

I keep my writings in two places:

blog.jez.io for technical posts
jez.io/thoughts/ for non-technical musings

Recently, I’ve been writing about Haskell, types, programming, and Vim (among others) if you prefer to browse by topic.

Some selected articles:

Code Review from the Command Line

I do the bulk of my code review from the command line, especially when reviewing larger changes. This post explores why and how I do this.
Union Types in Flow & Reason

Union types are powerful yet often overlooked. This post explores some of the tradeoffs in the way Flow implements union types versus ReasonML.
Profiling in Haskell for a 10x Speedup

I wanted to learn how to make Haskell code faster, so I solved a toy problem with a naive algorithm, and then profiled away the slow parts.
Variables and Binding

Variables are central to programming languages, yet they’re often overlooked. This post walks through three approaches to implementing variables.
Social. Private. Open. Pick Three

I no longer use Facebook. This post outlines why I made this decision, and what I use for communicating with people instead.

Talks

I mostly prefer writing, but from time to time I give talks.

─▶ jez.io/talks/

Work

My heart is in the work.

Andrew Carnegie

I’m currently very satisfied with my work! But if you work on programming languages or language-aware IDE tooling I’m always willing to chat. (At the very least, it’s always fun to swap notes on unique approaches to common problems.)

I’ve been lucky enough to work at a number of great companies:

Stripe - Sorbet

Jan 2022 - ···

I’m once again working mainly on Sorbet (the type checker, not the compiler). My current focus is improving Sorbet’s performance on large codebases and the experience of using Sorbet within an editor. This involves moving from batch processing to a more incremental architecture, building a parser that’s more tolerant of syntax errors, and building new language-aware, IDE-like features into Sorbet.
Stripe - Sorbet Compiler

Jan 2020 - Dec 2021

I spent two years building the Sorbet Compiler, an experimental ahead-of-time compiler translating Ruby source code to machine code. The architecture of the compiler essentially used Sorbet as the compiler frontend, LLVM as the compiler backend, and the Ruby VM and it’s C extension APIs as a language runtime. The Sorbet Compiler’s main goal is improving latency on Stripe’s live API traffic.
Stripe - Sorbet

Aug 2018 - Dec 2019

Starting in my second year at Stripe, I joined the team building Sorbet, a static type checker for Ruby. I developed new type system features for it, and ran large-scale code migrations to drive adoption of Sorbet in Stripe’s codebase. Stripe has millions of lines of Ruby and hundreds of developers, so we see adding types to Ruby as a key way to improve developer productivity.
Stripe - Stripe Elements

Aug 2017 - Aug 2018

I spent a year doing frontend development on Stripe Elements, a JavaScript UI library for collecting payment information. We emphasized cross-platform compatibility, rigorous types and testing, and high product quality.
Stripe - Stripe Checkout

May 2016 - Aug 2016

When I interned at Stripe, I worked on improving the developer experience of Checkout. Checkout is often a developer’s first experience with Stripe, so we wanted to make sure the onboarding experience was top notch.
Dropbox - Dropbox Paper

May 2015 - Aug 2015

When I interned at Dropbox, I worked on Paper. Paper is a collaborative workspace for teams. My specific project was to add rich embeds for things like YouTube videos and Google Docs.
Bloomberg

May 2014 - Aug 2014

When I interned at Bloomberg, I worked on an internal financial simulation tool in C++ that enabled developers to prototype and test their apps.

Other interests