The Syntax of the Boeotian Dialect Inscriptions

In other words, it's pure syntactic sugar. Most folks either always use #' before LAMBDA expressions in value positions or never do. In this book, I always use #'. 67 Dynamic variables are also sometimes called special variables for reasons you'll see later in this chapter. It's important to be aware of this synonym, as some folks (and Lisp implementations) use one term while others use the other. 68 Early Lisps tended to use dynamic variables for local variables, at least when interpreted. Elisp, the Lisp dialect used in Emacs, is a bit of a throwback in this respect, continuing to support only dynamic variables. Other languages have recapitulated this transition from dynamic to lexical variables—Perl's local variables, for instance, are dynamic while its my variables, introduced in Perl 5, are lexical. Python never had true dynamic variables but only introduced true lexical scoping in version 2.2. (Python's lexical variables are still somewhat limited compared to Lisp's because of the conflation of assignment and binding in the language's syntax.) 69 Actually, it's not quite true to say that all type errors will always be detected—it's possible to use optional declarations to tell the compiler that certain variables will always contain objects of a particular type and to turn off runtime type checking in certain regions of code ...»