On 2017-07-13 23:29, Atrudyjane via Haskell-Cafe wrote:
runRolls :: State RollsState RollsValue runRolls = do (l, s, c, sg, xs) <- get if (s >= l) then return (c, reverse xs) else do let (d, ng) = randomR (1, 6) sg put (l, s + d, c + 1, ng, intToDie d : xs) runRolls
rollsCountState :: Int -> IO () rollsCountState n = print $ evalState (runRolls) (n, 0, 0, mkStdGen 0, [])
I'm wondering if that 'do' block under the else is a not so great stylistic choice. If the 'let' and 'put' is moved above the 'if', then that's just an unnecessary call at the end. Or is it just the nature of running inside a monad?
It is the nature of running inside a monad. But at the same time, runRolls contains the implementation of two things. Which, to a purist like me, would be one too many. Pulling one of them out into a second function already makes this one much nicer. But there are other, more pressing stylistic choices to make. Namely to use records and mnemonic names. Here is an adapted version taken to more beauty and then beyond into ridiculousness: {-# LANGUAGE RecordWildCards , MultiWayIf #-} […] rollsCountState :: Int -> IO () rollsCountState rollLimit = print $ evalState runRolls initialRollState where runRolls = get >>= \RollsState{..} -> if | rollSum >= rollLimit -> pure (rollCount, reverse rolledDice) | otherwise -> modify rollDice >> runRolls The “ideal” version is probably somewhere in between. Maybe with one of the many whileM or untilM implementations thrown in that everyone keeps reinventing. Cheers, MarLinn