>>> import AtCoder.Extra.AhoCorasick qualified as AC
>>> import Data.Vector.Unboxed qualified as VU

Pattern strings must be given as V.Vector (VU.Vector Int):

>>> let patterns = V.fromList [VU.fromList [0, 1], VU.fromList [0, 2], VU.fromList [2, 3, 4]]
>>> let ac = AC.build patterns
>>> AC.size ac
7

The automaton could be run manually with next or nextN:

>>> AC.nextN ac {- empty node -} 0 (VU.fromList [0, 2, 3])
5

match returns a vector of (endPos, patternId):

>>> --                         [.....) pattern 0
>>> --                               [.......) pattern2
>>> AC.match ac $ VU.fromList [0, 1, 2, 3, 4]
[(2,0),(5,2)]

If you need a vector of (startPos, patternId), you must manually map the result:

>>> let f (!end, !patId) = (end - VU.length (patterns V.! patId), patId)
>>> --                                    [.....) pattern 0
>>> --                                          [.......) pattern2
>>> VU.map f . AC.match ac $ VU.fromList [0, 1, 2, 3, 4]
[(0,0),(2,2)]

Note that duplicate patterns are only counted once with match.