Ticket #1376: StateAccum.hs
| File StateAccum.hs, 503 bytes (added by logancapaldo@…, 6 years ago) |
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| 1 | import Control.Monad |
| 2 | import Control.Monad.State |
| 3 | import Control.Monad.List |
| 4 | |
| 5 | sumUp :: [Int] -> State Int [()] |
| 6 | sumUp = sequence . map (modify . (+)) |
| 7 | |
| 8 | type StateWithList = ListT (State Int) |
| 9 | |
| 10 | sumUp' xs = do x <- xs |
| 11 | lift (modify (+x)) |
| 12 | return (lift get) |
| 13 | |
| 14 | |
| 15 | sumThreeLists :: [Int] -> [Int] -> [Int] -> Int |
| 16 | sumThreeLists xs ys zs = execState (sumUp xs >> sumUp ys >> sumUp zs) 0 |
| 17 | |
| 18 | main = do print $ execState (sumUp [1,2,3]) 0 |
| 19 | print $ sumThreeLists [1..10] [1..10] [1..10] |
