(guile.info.gz) Lexical Scope

 
 14.4.4 Lexical Scope
 --------------------
 
 The rules that we have just been describing are the details of how
 Scheme implements "lexical scoping".  This subsection takes a brief
 diversion to explain what lexical scope means in general and to present
 an example of non-lexical scoping.
 
    "Lexical scope" in general is the idea that
 
    * an identifier at a particular place in a program always refers to
      the same variable location -- where "always" means "every time
      that the containing expression is executed", and that
 
    * the variable location to which it refers can be determined by
      static examination of the source code context in which that
      identifier appears, without having to consider the flow of
      execution through the program as a whole.
 
    In practice, lexical scoping is the norm for most programming
 languages, and probably corresponds to what you would intuitively
 consider to be "normal".  You may even be wondering how the situation
 could possibly -- and usefully -- be otherwise.  To demonstrate that
 another kind of scoping is possible, therefore, and to compare it
 against lexical scoping, the following subsection presents an example
 of non-lexical scoping and examines in detail how its behavior differs
 from the corresponding lexically scoped code.
(guile.info.gz) Lexical Scope

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