I don't really have much out there right now. I have some spec, but it's really out of date. I have done some ML and I would say that while patten matching/powerful type inference are important to the language, in a lot of other ways my language won't feel as limiting as a purely functional language like ML. One of the important things I think a modern programming language needs are functional components that can be used when necessary. An example is annotating when you want the compiler to verify that a given function is a pure function(no side effects). This allows the compiler to make certain optimizations in both removing computation when results are ignored, and massively helps with concurrency(functions can be run in parallel when you have the guarantee that they won't interfere).