Hi, I'm developing toy application to learn HDBC. I have "problem" with doing relations mapping. Actually I don't know is it a problem or "feature". ;) Anyway, I have two tables with relation between them: (this example is simplified to the whole structure of database, you can imagine) CREATE TABLE TD_set ( setId INTEGER PRIMARY KEY, setName TEXT NOT NULL ) CREATE TABLE TO_card ( cardId INTEGER PRIMARY KEY AUTOINCREMENT, setId INTEGER NOT NULL," -- Relation to TD_set setSeq INTEGER NOT NULL ) (no foreign key as sqlite3 does not care anyway - at least AFAIK) And in Haskell:
type CardSet = String
data Card = Card { set :: CardSet, seqNo :: Integer, }
There is no problem with filling the structure Card with "seqNo" but I can't fill "set". I would have to put there IO (CardSet) but I don't want to do that as whole structure returned from my mapping function is already inside IO monad. Can I do it? Here is my (perfect) function - http://hpaste.org/5839 . See "getCards" and some helper functions. This does not compile as (I believe) getElement wants to return IO (CardSet) Thank you in advance for all your input. Radek.