How can I achieve that I can pass named function arguments from a named vector?

```
vec <- c(b=5, a=3)
fun <- function(a, b) {
  browser()
  message(sprintf("a=%s", a))
  message(sprintf("b=%s", b))
}
fun(vec) # should return a=3, b=5

```

I mean in this example, I want to dynmically pass the values from `vec` into `fun` without doing `a=vec$a`, `b=vec$b`?