The talk discusses HPC (High Performance Computing) and the challenges faced when working with Nix. The speakers work on a parallel, concurrent task-based runtime and need to work with a compiler that can read pragmas and transform them to function calls to the runtime. Performance is critical, and workloads are executed on hundreds or thousands of CPUs. The talk explores how to benefit from using Nix without root access, as HPC environments often have old kernels and software stacks. Solutions discussed include using name spaces, custom packages, compilers, and an isolated environment for building applications. Challenges faced include preventing code from loading anything outside the Nix store and dealing with in-care libraries on the system. Some questions addressed include storage limitations and the possibility of sharing the Nix store among users.