Open Shading Language (OSL) is a small but rich language for programmable shading in advanced renderers and other applications, ideal for describing materials, lights, displacement, and pattern generation.
https://open-shading-language.readthedocs.io/en/main/
https://github.com/AcademySoftwareFoundation/OpenShadingLanguage
https://github.com/sambler/osl-shaders
Learn OSL in a few minutes
https://learnxinyminutes.com/docs/osl/
