I can't believe something like this makes it into "production". How could anybody value such an asinine type inference system over compile time?
If your compiler needs a constraints solver to determine the type of an expression, it belongs in a science exhibit, not into a real-world toolchain.
Don't try to be clever! Give me a compiler that's predictable, reliable and fast. If that means I have to add some type information here and there, that's just fine!