20. Libraries

Use require and provide to make functions from one file available in another file.

Require and provide

Require loads functions from another file. Provide makes functions available for other files to load.

Require

In order to use the functions in another file, you need to require that file. You already know (require picturing-programs) but when we use require we need to give the whole filename.

(require "posn-util.rkt")

Provide

The provide command makes functions available for other files to use. One way to use it is to list all of the functions you want to allow other files to use:

(provide posn-add posn-sub posn-scale posn-distance)

Sometimes you just want to make every function in the file available. There is a shortcut to do that:

(provide (all-defined-out))