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(guile.info)About Closure

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The Concept of Closure
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The concept of "closure" is the idea that a lambda expression
"captures" the variable bindings that are in lexical scope at the point
where the lambda expression occurs.  The procedure created by the
lambda expression can refer to and mutate the captured bindings, and the
values of those bindings persist between procedure calls.

This section explains and explores the various parts of this idea in
more detail.

About Environments

Names, locations, values and environments.

Local Variables

Local variables and local environments.

Chaining

Environment chaining.

Lexical Scope

The meaning of lexical scoping.

Closure

Explaining the concept of closure.

Serial Number

Example 1: a serial number generator.

Shared Variable

Example 2: a shared persistent variable.

Callback Closure

Example 3: the callback closure problem.

OO Closure

Example 4: object orientation.