2.8.1 Procedures ¶

Procedure: page-next? page-number total-pages ¶

Tell whether there is a next page after the current page-number according to total-pages.

Specification:

page-number (natural): Natural number representing the current page in a collection of pages.

total-pages (natural): Natural number representing the total number of pages in the collection.

Return value (boolean): True if the page after page-number exists. Otherwise, false.

Examples:

> (page-next? 5 20)
#t

> (page-next? 20 20)
#f

Procedure: page-prev? page-number OPT: start-page ¶

Tell whether there is a previous page before page-number according to start-page.

Specification:

page-number (natural): Natural number representing the current page in a collection of pages.

start-page (natural): Optional. Natural number representing the first page in a collection of pages.

If not provided, it defaults to 1.

Return value (boolean): True if the page before page-number exists. Otherwise, false.

Examples:

> (page-prev? 2)
#t

> (page-prev? 1)
#f

> (page-prev? 4 3)
#t

> (page-prev? 3 3)
#f