Explore the process of running custom languages on GraalVM in this 49-minute conference talk from Devoxx Poland 2019. Discover how GraalVM supports multiple languages on the Java Virtual Machine, including JavaScript, Ruby, and Python. Learn the steps required to implement and run a new language in GraalVM, using Brainfuck as an example. Gain insights into the benefits of GraalVM, such as fast runtime and excellent tooling support. Understand how to integrate guest languages within Java applications, providing a fun and educational exploration of language implementation on this versatile virtual machine.