Optimising your notation to not confuse people in the first 10 minutes of seeing it but to hinder readability ever after is a really bad mistake.

The impression that the phrase “this interface feature is intuitive” leaves is that the interface works the way the user does, that normal human “intuition” suffices to use it, that neither training nor rational thought is necessary, and that it will feel “natural.” We are said to “intuit” a concept when we seem to suddenly understand it without any apparent effort or previous exposure to the idea.



It is clear that a user interface feature is “intuitive” insofar as it resembles or is identical to something the user has already learned. In short, “intuitive” in this context is an almost exact synonym of “familiar.”



The term “intuitive” is associated with approval when applied to an interface, but this association and the magazines’ rating systems raise the issue of the tension between improvement and familiarity. As an interface designer I am often asked to design a “better” interface to some product. Usually one can be designed such that, in terms of learning time, eventual speed of operation (productivity), decreased error rates, and ease of implementation it is superior to competing or the client’s own products. Even where my proposals are seen as significant improvements, they are often rejected nonetheless on the grounds that they are not intuitive.



It is a classic “catch 22.” The client wants something that is significantly superior to the competition. But if superior, it cannot be the same, so it must be different (typically the greater the improvement, the greater the difference). Therefore it cannot be intuitive, that is, familiar. What the client usually wants is an interface with at most marginal differences that, somehow, makes a major improvement. This can be achieved only on the rare occasions where the original interface has some major flaw that is remedied by a minor fix.

(_+_)

Or as Jef Raskin put it:Complaining that a programming language “Violates the Principle of Least Surprise” is a complaint that it fails to appeal at first glance, without any training or investigation. But if a new language is “intuitive,” it can only offer you a marginal improvement over the languages you already know well.You needn’t look at functional langauges like Scala to see this at work. Is Ruby’s for loop an improvement over Java? By how much? Ruby’s big win over Java in that regard is the ease with which you can use Enumerable’s collect, select, detect, and inject methods . Which, of course, are not familiar to the programmer with a grounding in for loops. They require study to understand. But once understood, they make code easier to read thereafter.post scriptum:As Justin points out in the comments, the real meaning of the “Principle of Least Surprise” is that languages should be consistent. The principle applies to how the language behaves when you already know something about it. So if you see, the questions is whether this makes sense if you already know that underscore is a function parameter.And more: The word "intuitive"... isn't. And even more, from Matz in Japanese: http://www.rubyist.net/~matz/20080108.html#p02