What I mean in ML syntax, every function is a curried function of only one argument. So you don't know how many arguments a function has without looking up its type. In concatenative languages, this is similar, every function (with exception of special forms) is a function from stack to stack, and to see how many arguments it has you also have to look at its type.

I think concatenative syntax is in fact more elegant than ML syntax, since it also "curries" return values, and is evaluated in the same order as written.