Decided once per run from formals(), never by probing the simulator: a
wrong guess would produce a wrong posterior with no error.
Value
"named" (one scalar per formal) or "vector" (the named parameter
vector as the first argument).
Details
A partial match warns. When some parameter names appear among the formals and others do not, both signatures are plausible and the vector form wins, which sends the whole parameter vector to the first formal and lets the rest take their defaults. That trains on nonsense without erroring, and one typo in a prior name is enough to cause it. A warning rather than an error, because a vector-signature simulator whose first argument happens to carry a parameter's name is legal.