This module encapsulates "The C version of the libstemmer library" from the Snowball project. This library provides stemmers in a variety of languages. The interface to this library is very simple:

• snowball/3 stems a word with a given algorithm
• snowball_current_algorithm/1 enumerates the provided algorithms.

Here is an example:

?- snowball(english, walking, S).
S = walk.

See also

- http://snowball.tartarus.org/

 snowball(+Algorithm, +Input, -Stem) is det

Apply the Snowball Algorithm on Input and unify the result (an atom) with Stem.

The implementation maintains a cache of stemmers for each thread that accesses snowball/3, providing high-perfomance and thread-safety without locking.

Arguments:

Algorithm	- is the (english) name for desired algorithm or an 2 or 3 letter ISO 639 language code.
Input	- is the word to be stemmed. It is either an atom, string or list of chars/codes. The library accepts Unicode characters. Input must be lowercase. See downcase_atom/2.

Errors

- domain_error(snowball_algorithm, Algorithm)

- type_error(atom, Algorithm)

- type_error(text, Input)

 snowball_current_algorithm(?Algorithm) is nondet

True if Algorithm is the official name of an algorithm suported by snowball/3. The predicate is semidet if Algorithm is given.