LISP: Scope and extent in lisp

1. Scope and Extent in Lisp

3. The kind of expression in which the reference takes place.

4. The location of the reference within the program text.

9. Dynamic extent: references may occur at any time between the establishment of the entity and the explicit disestablishment of the entity.

10. Indefinite extent: this entity continues to exist as long as the possibility of the reference remains.Most common Lisp data objects have indefinite extent.

12. Ex: ( defun compose( f g) # ‘ (lambda (x) (funcall f (funcall g x)))) The parameter bindings for f and g do not disappear because the returned function, when called, could still refer to those bindings. ( funcall (compose #’ sqrt # ‘ abs) -9.0) Produces the value 3.0

14. Their bindings are visible beginning at a certain textual location in the defining form and continuing through the textual end of the defining form.

15. Any reference to a textually identical name from outside of the defining name must refer to a different binding.

17. A binding is created for a special variable as the result of the executing some form in your program.

18. The scope of the dynamic form extends into any form ( called directly or indirectly) by the form which established the dynamic binding.