Thank you Rohit, at a first glance it seems to compile but ...
r = RandomReal[{-1, 1}, {1000000, 2}];
r // EstimatedArc; // AbsoluteTiming
r // EstimatedArcC; // AbsoluteTiming
r // EstimatedArcM; // AbsoluteTiming
(*
{0.591217, Null}
{0.095182, Null}
{0.657469, Null}
*)
... it performs even slower than the non compiled version.
