It has long since been cleaned up, but the history of Lucene's Levenshtein automatons are a fascinating mix of pragmatism, hackery, grit, and engineering. Using a Python library to generate crazy-looking Java code, which you can't (yet) understand, but whose tests pass and benchmarks look amazing.

- https://blog.mikemccandless.com/2011/03/lucenes-fuzzyquery-i... - https://www.youtube.com/watch?v=4AbcvHKX8Ow

(Levenshtein distances are used as a measure between fuzzy/misspelled matches, and was ironically misspelled initially - https://lucene.apache.org/core/7_4_0/suggest/org/apache/luce...)