Oh, I didn't mean to suggest that it automatically binds. My second suggestion for how to achieve this does require some sort of automation. If you create a closure from Str::someMethod($arg1, $arg2) where someMethod isn't static, it should create a closure with the signature fn(Str $object, $arg1, $arg2), which would wrap a call to [$object, 'someMethod]($arg1, $arg2).
However, perhaps the simplest solution, and one that could be done realtively easily and quickly, would be to delay the error, and allow static closures to bound with Closure::bind() if they represent a non-static method. --- Best Regards, *Ollie Read*