This was my very original programming language. It's a bit rough around the edges, as I didn't really know what I was doing.
Because I didn't know what an AST was, I devised a special way to parse things: the colon, or as it's called internally, applier.
Each sequential : indicates that more arguments should be passed to the first value. So for if:(foo):{bar}:{baz}, this is running the
internal if function with the arguments (foo), {bar}, and {baz}. Not great, but it's a workaround.