Summary

In this chapter, we've looked at two significant functional programming topics. We've looked at recursions in some detail. Many functional programming language compilers will optimize a recursive function to transform a call in the tail of the function to a loop. In Python, we must do the tail-call optimization manually by using an explicit for loop instead of a purely function recursion.

We've also looked at reduction algorithms including sum(), count(), max(), and min() functions. We looked at the collections.Counter() function and related groupby() reductions.

We've also looked at how parsing (and lexical scanning) are similar to reductions since they transform sequences of tokens (or sequences of characters) into higher-order collections with more complex properties. We've examined a design pattern that decomposes parsing into a lower level that tries to produce tuples of raw strings and a higher level that creates more useful application objects.

In the...