ms-0.2.1: CHANGELOG.md

0.2.1
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* Added a changelog.
* Added `hamming` distance metric.
* Added instance of `Semigroupoid`. (@tonymorris)
* Fixed hlint warnings.

0.2
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* Fixed types of `discrete` and `levenshtein` to use `Integral` instead of
  `Floating`.
* Slight docs formatting fixes

0.1
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Initial release.