Didn't think of "par", cool idea. It could even be turned into a macro, like that:
(par foo x) => [foo x] ; Well maybe too much.
About flip, I'd rather rotate the arguments instead of reverse them. That way, you have access to more arguments orders by composing flip. You could also define flip2, flip3... in the library if they're used often.
Don't you mean [foo x] => (par foo x)? []s aren't fundamental, they're sugar.
I'm not sure there is a sensible way to extend flip to functions taking more than two arguments. Reverse is one, rotate is another; you might as well have two functions for that. It seems like six of one, half a dozen of the other to me.
