vas-string-metrics provides the Jaro, Jaro-Winkler, Levenshtein, and
normalized Levenshtein string distance/similarity metrics algorithms.

The Jaro (function jaro-distance), Jaro-Winkler (function
jaro-winkler-distance) and normalized Levenshtein (function
normalized-levenshtein-distance) algorithms return a number in the
range 0 to 1 indicating how similar two given strings are - where 0
indicates no similarity, and 1 indicates a perfect match.

The Jaro-Winkler metric is a heuristic suitable for shorter strings
(such as place and people names), while the Levenshtein distance is
computed as the minimum number of insertions, deletions, or
substitutions needed to transform one string into the other (function
levenshtein-distance).

The code is distributed under the terms of the LLGPLv3 (see LICENSE
for details), except for the unit tests, which are in the public
domain.