NOTE : read the rest of the series, or check out the source code.
If you enjoy reading these exercises then please buy Crista’s book to support her work.
Following on from the last post, we will look at the Infinite Mirror style today.
Style 7 – Infinite Mirror
This style is really all about recursions.
- All, or a significant part, of the problem is modelled using induction.
First, let’s get the list of stop words and put them in a set:
and then we will implement the counting logic using recursion:
I made some adjustments to Crista’s version here. In her version, wordFreqs is a global state that has been passed in as argument but the recursive count function returns nothing.
In my implementation, although I’m still using a mutable dictionary, it’s an implementation detail that is not exposed to the outside world. I could have used a Map here instead, but constantly updating a Map is really clumsy, plus Map performs really poorly in this type of use pattern.
Then we have another recursive functions, for printing out the word frequencies:
and then some code to tie everything together:
You can find all the source code for this exercise here.
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