Ryan Ingram said: > Interesting, although this seems like a perfect use for "orelse": > > > wait_stm :: Wait a -> STM a > > wait_stm (Wait w) = readTVar w >>= maybe retry return > > > wait :: Wait a -> IO a > > wait w = atomically $ wait_stm w > > > wait_first :: [Wait a] -> IO (a, [Wait a]) > > wait_first [] = error "wait_first: nothing to wait for" > > wait_first ws = atomically (do_wait ws) where > > do_wait [] = retry > > do_wait (w : ws) = do > > r <- wait_stm w > > return (r, ws) > > `orelse` fmap (second (w:)) (do_wait ws)
Indeed, that is very nice. I see now that orElse allows wait_stm to compose easily, so you don't need to keep opening up the insides of the Wait variable. _______________________________________________ Haskell-Cafe mailing list [email protected] http://www.haskell.org/mailman/listinfo/haskell-cafe
