Jesper Eskilson

Erlang Community Lead and Senior Engineer at Klarna

Jesper is a senior engineer with a background in compiler development and IDE tooling. He currently works at Klarna, maintaining a large and highly available distributed Erlang system. He oftens finds himself improving build systems and fixing errors in static code analysers. When he isn't working, he is doing cross-stitch embroidery and using GPS to find plastic containers in the woods.

Past Activities

Jesper Eskilson
Code BEAM Europe 2022
19 May 2022
14.40 - 15.25

Slaying the Type Hydra, or How We Went from 12,000 Dialyzer Errors to None

Have you ever tried running Dialyzer on a large Erlang project for the first time? Did you also get thousands of cryptic errors? Three years ago at Klarna we stood at 1.7MLOC with 12k Dialyzer errors. This is the point where you typically through up your hands and walk away. But we didn't. We fought. And now we are up to 1.72MLOC, but completely free of Dialyzer errors. This talk is about our fight, but not just the fun war stories. You will get a detailed plan for slaying the type Hydra, no matter how many heads it grows.

The aim is to get people excited about fixing Dialyzer errors in large code bases, to convince them that it can be done, even when there are lots of errors.

Erlang/Elixir developers in general, and developers maintaining large and/or legacy systems in particular, who would like to run Dialyzer on their code, but are limited due to the number of existing errors in the code.