Hi, I'm new to STM and to Haskell in general. I've been writing a small library to try some graphics algorithms in Haskell, but using GLFW's callbacks seems to be causing me problems. I have a (relatively heavyweight?) object wrapped in a TVar (Data.Set) that I'm sharing across all threads. Unfortunately, once I run the program, it becomes unresponsive although the main loop is still running. I'm not sure exactly what the semantics are for getting STM right, but ideally I'm trying to modify the TVar in GLFW event callbacks and then finally read out the value of the TVar at the end (or beginning) of my rendering loop. I've been able to get a small program working that reproduces my problem: https://gist.github.com/Mokosha/34eda7bd2d6b5cafd5a3 Any help would be great! Thanks! - Pavel