FromField instance for TSVector

[delanoe]

Hello,
TSVector type of Postgres is the following:
https://www.postgresql.org/docs/8.3/datatype-textsearch.html
Example of tsvector: "'cat':2 'dog:5 'animal':10"

To add the FromField instance we need a parser.
Do you have an example of implementation that could help to parser for the TSVector FromField instances ?

Specifications would be the following:
type TSVector = [Vector]
data Vector = Vector { text :: Text
, position :: Int
}

Many thanks for your help