Lambda the Ultimate

I'm not sure I'd call "full?" cryptic at this point—it's become a pretty popular convention. Still, it has always driven me nuts that an ostensible question, "is it full", could return true or false. I'm a fan of "fullp", which is more cryptic but at least is an assertion which can be true or false. OTOH, if naming conventions for predicates are a language's biggest flaw, the designer ought to be feeling pretty good.

And for the record, I think the same thing about C. Especially about how * plays double duty.

What is the "p" in "fullp"? Predicate? And for the record, I still haven't gotten past the naming conventions in my learning process. I was distracted. ;)

Using ? at the end of predicates is the standard convention used by Scheme (null?, prime?, etc...). The reason most other languages don't use this convention is that most are limited to alphanumeric and underline in their naming conventions. Anyhow, I haven't seen any confusion in Scheme over this naming convention.

Can't say I like the ?full convention for "if full", but such idioms have a tendency to become natural once you get into the culture of a language. Which is actually the bigger issue with learning any language - you have to accept quite a few idioms that come with the community for any particular PL.

Yes, it's for predicate. It comes from the non-Scheme side of the Lisp family. I like it because predicates are labeled, but not with a non-pronouncing character. Plus the whole "Is it full?" "True." "Uhhh....".

...and other places where the type of a term is arbitrarily "encoded" somehow in its name. By "arbitrary", I mean in situations where the type (or representation of a type) isn't manifest from the functional description. I know I'm splitting hairs here...

It's especially obnoxious when you're dealing with a type that the compiler/language in question can represent. (It's a different matter, I suppose, when dealing with domain types which are narrower than what the type system can handle--Hungarian notation here can better express intent--but still kinda kludgy).

If you want to specify the type of a term, it is best to do so formally.

Are-you-full-good-sir?

As someone who done a small amount of programming in Forth, conventions that use @ and ! and ? for load, store and query as a common idiom ensures that understanding of new code becomes that much easier. Factor draws from a Forth base as well as Scheme and the conventions in place are there for comprehension.

I find Java and C# and others of that ilk to be more difficult to pick up than something like Factor which really only has two basic modes - parsing words which typically end in : or RPN words which affect and use the stack.

To state the obvious, all programming languages have idiomatic ways of expressing ideas and once the idioms are understood, then well written programs are that much easier to understand.

In the case of Factor, the use of non-alphabetic characters in word names actually makes reading the code that much easier to comprehend. Some idioms that have developed in Factor are strange, I have problems with Fry but even there it becomes a matter of understanding the idiom (semantics) being expressed.

In your comments about C, I recall a comment being made about a snippet of code that uses multiple *'s and trying to determine the actual meaning of this snippet. Many languages have anomalous syntactic structures that give rise to misunderstanding on the part of those trying to read the code, witness all the obfuscated programming contests that abound. Constructive consistency is not a common attribute of mankind.

full? and ?full are standard Forth conventions dating back to the 1970s.