Lexical Environments

ToC

Allegro CL

ANSI Common Lisp

3 Evaluation and Compilation

3.1 Evaluation

3.1.1 Introduction to Environments

3.1.1.3 Lexical Environments

A lexical environment for evaluation at some position in a program is that part of the environment that contains information having lexical scope within the forms containing that position. A lexical environment contains, among other things, the following:

bindings of lexical variables and symbol macros.
bindings of functions and macros. (Implicit in this is information about those compiler macros that are locally disabled.)
bindings of block tags.
bindings of go tags.
information about declarations.

The lexical environment that is active at any given position in a program being semantically processed is referred to by definite reference as "the current lexical environment," or sometimes as just "the lexical environment."

Within a given namespace, a name is said to be bound in a lexical environment if there is a binding associated with its name in the lexical environment or, if not, there is a binding associated with its name in the global environment.

3.1.1.3.1 The Null Lexical Environment