Snowball is a small string processing language for creating stemming
algorithms for use in Information Retrieval, plus a collection of
stemming algorithms implemented using it.
Snowball was originally designed and built by Martin Porter. Martin
retired from development in 2014 and Snowball is now maintained as a
community project. Martin originally chose the name Snowball as a
tribute to SNOBOL, the excellent string handling language from the
1960s. It now also serves as a metaphor for how the project grows by
gathering contributions over time.
The Snowball compiler translates a Snowball program into source code in
another language - currently Ada, ISO C, C#, Go, Java, Javascript,
Object Pascal, Python and Rust are supported.
What is Stemming?
Stemming maps different forms of the same word to a common "stem" - for
example, the English stemmer maps connection, connections, connective,
connected, and connecting to connect. So a search for connected would
also find documents which only have the other forms.
This stem form is often a word itself, but this is not always the case
as this is not a requirement for text search systems, which are the
intended field of use. We also aim to conflate words with the same
meaning, rather than all words with a common linguistic root (so awe and
awful don't have the same stem), and over-stemming is more problematic
than under-stemming so we tend not to stem in cases that are hard to
resolve. If you want to always reduce words to a root form and/or get a
root form which is itself a word then Snowball's stemming algorithms
likely aren't the right answer.
