JET.jl: The next generation of code checker for Julia
2021-07-30, 12:30–13:00 (UTC), Blue

Julia's extreme expressiveness and composability come from its dynamism – at the cost of that, a static type check of Julia code has been remained as a longstanding problem.
JET.jl is a fresh approach to static analysis of such a dynamic language; it can detect type-level errors given a pure Julia script within a practical speed.
In this talk we will first give an overview of its features and basic usages, and then move to a discussion of its internals, current limitations and future works.

This talk will introduce JET.jl, an experimental type checker for Julia.

JET is powered by both abstract interpretation routine implemented within the Julia compiler as well as a concrete interpretation based on JuliaInterpreter.jl. The abstract interpreter enables a static analysis on a pure Julia script without any need for additional type annotations, while the concrete interpreter allows effective analysis no matter how heavily it depends on runtime reflections or external configurations, which are common obstacles to static code analysis.

The talk will begin by explaining the motivation for type-level analysis of Julia code as well as how we can find various kinds of errors ahead of time using JET. Then we will illustrate how JET works and also the limitations involved with its design choices, and finally discuss the planned future enhancements like IDE integrations and such.

A research programmer working at Julia Lab, MIT. Working on Julia's compiler technology stack, mainly around its abstract interpretation based type inference. Also a maintainer of Julia IDEs, julia-vscode and Juno.

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