(I've been editing this post on and off for almost a year. I'm not really happy with it, but I suspect I never will be.) Several months ago I gave a talk at work about Hindley-Milner type inference. When I agreed to give the talk I didn't know much about the subject, so I learned about it. And now I'm writing about it, based on the contents of my talk but more fleshed out and hopefully better expl