romkan-hs is a library for converting between Japanese romaji and Japanese kana.
It is a port of python-romkan.
cabal install romkan
$ ghci
Prelude> :set -XOverloadedStrings
Prelude> import NLP.Romkan
Prelude NLP.Romkan> import qualified Data.Text.IO as T
Prelude NLP.Romkan T> T.putStrLn $ toRoma "かんじ"
kanji
Prelude NLP.Romkan T> T.putStrLn $ toHiragana "kanji"
かんじ