Implements full text indexation (indexText) and text search(contains), as an addition to the query language implemented in IndexQuery it also can index the lists of elements in a field (with indexList) so that it is possible to ask for the registers that contains a given element in the given field (with containsElem)

An example of full text search:

data Doc= Doc{title, body :: String} deriving (Read,Show, Typeable)
instance Indexable Doc where
  key Doc{title=t}= t

instance Serializable Doc  where
  serialize= pack . show
  deserialize= read . unpack

main= do
  indexText  body T.pack
  let doc= Doc{title=  title, body=  hola que tal estamos}
  rdoc <- atomically $ newDBRef doc
  r1 <- atomically $ select title $ body contains hola que tal
  print r1

atomically $ writeDBRef rdoc  doc{ body=  que tal}
  r <- atomically $ select title $ body contains hola que tal
  print r
  if  r1 == [title doc] then print OK else print FAIL
  if  r== [] then print OK else print FAIL