are there anonymous, type-safe, general nominee signatures c# 2.0?

consider nominee general a b function:

public nominee b fun<a, b>(a x);

i following duty accepts invokes fun delegate:

public stationary b invokefun<a, b>(a x, fun<a, b> f)
{ relapse f(x); }

(never mind presumably correct invokefun.)

can i invokefun but naming fun delegate? i design something work, nonetheless doesn't:

public stationary b invokefun<a, b>(a x, b (a) f)
{ relapse f(x); }