This is very interesting, and I’ve been thinking of doing the same. From a cursory reading of the code, it looks like you mutate all operators in the file at the same time instead of one by one. Is that so? Shouldn’t one mutate one operator at the time to get more precise results?
To reduce the need to recompile a module lots of times, I’ve also tried to do it in a different way by mutating the Erlang AST in a way that allowed me to toggle mutations on and off without recompiling the code (see here: https://nwolverson.uk/devlog/2016/08/01/introducing-purescript-erlang.html), but I couldn’t get very good error messages on my first try. It also made it harder to generate relevant mutations (and it made it impossible to generate mutations on macros)
