I taught Huey to come when I call him. He gets the intermittent reward of a treat (sometimes there is a food treat, sometimes there is not, and what he gets is a little scratch and a "good boy!"). I don't call him over if I'm going to halter him up and make him work (or, at least, not yet). So he's learned that when I call him it often means something Nice and it doesn't mean something Nasty. I have a special tone I use for calling him, so he doesn't get confused if I'm just talking about him.
When I decided to do this, it wasn't because he was hard to catch but because he really likes to hang out in the nastiest, muddiest part of his paddock, and I didn't want to have to wade in there after him.