13 - A small Scheme application
The problem when writing programs in a functional programming language, such as Scheme, is debugging. The trick is to create a logical plan that builds up the application as you go. Test each sub-command and each command. Create named functions - get them working - and then park them at the top of the program as you go.
This technique may be slower than you would like, but it works. It also saves you hours of debugging.
The code used in this video can be found via https://lyw4.life/Resources/scheme.php.