In posting messages about the new for-each loop syntax in Java 5.0, many developers have complained about its crypticism. A for-each loop might look like:

for (Employee employee: department)
 terminate(employee);

You would read this for-each loop as, "for each employee (of type Employee) in department)." Many developers would have preferred something like:

for (Employee employee in department)
 terminate(employee);

But alas, Sun resists new Java keywords like "in" because they have the potential to break gobs of existing code.

It's not that big a deal to me, since I view the loop construct as idiomatic. Once I saw it and it was explained to me, or perhaps twice, it became ingrained. Subsequent encounters required no such explanation or even translation time.

Nonetheless, the new for-each loop is a slightly cryptic construct. Not quite as bad as the ternary operator (conditional ? true-value : false-value), but still not obvious the first time. Some developers can't stand it.

My take is that Java is a fairly cryptic language to start with, particularly if you have no background in C-based languages (C, C++, Objective C, C#, and whatever else). The old C-style for loop isn't obvious either. Typical C code is rife with odd characters such as *, %, &, {, }, and |.

This obvious observation led me to create Jeff's hypothesis of cryptics:

Jeff's Hypothesis of Cryptics: The crypticism of a language is directly proportional to the mean number of shift keystrokes required.

It's a pretty useless hypothesis, granted. But taking a look at a couple languages that appear on opposite ends of the spectrum shows that there is some validity. Curly braces in C-based languages { use the shift key, as does * (pointer dereference). The new generics stuff in 1.5 uses angle brackets < and >, both requiring use of shift. The tertiary operator uses both : and ?. Strings are set off by use of the " character. And C uses lots of parentheses.

Smalltalk, in contrast, uses brackets ([ and ]) to set off blocks. No shift-combination necessary! Boolean operators are spelled out instead of using & and |. Strings are set off by use of the ' character. The major exception to the rule is the use of the colon to designate a selector (but this also suggests that perhaps you should pass fewer parameters to your methods).

Of course, crypticism is related to how easy it is to read text, not write it. But it's no coincidence that the cryptics require shift-combinations on a standard keyboard or typewriter. These are the characters that make things difficult to read when used to excess.

I was curious enough to pose the idea to Dan Ingalls, who had a lot to do with the design of early Smalltalk implementations. He indicated that indeed there was a conscious effort to reduce the number of shift keystrokes required. This was due to the fact that one goal for Smalltalk was that children would be able to program in it.

Lots of shift-key combinations = lots of crypticism. I'm still amazed at the fact that modern languages retain so much of the unnecessary constructs and ugliness of a language that is 30 years old.