Land of Lisp

What You've Learned

In this chapter, we discussed functional programming. Along the way, you learned the following:

• Programs written in the functional style always give the same result when they are given the same values in their arguments.

• Functional programs do not contain side effects. Their whole purpose in life is to just calculate a value to return.

• Programs that are not functional usually read like a cookbook, with statements like, “First do this, and then do that.” This style of programming is called imperative programming.

• A good strategy for writing Lisp programs is to break them into a clean, functional part and a dirty, imperative part.

• Functional programs can be written quickly, are more compact, and tend to have fewer bugs, particularly ...