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  1. import Control.Monad.State
  2.  
  3. data Person = Person {
  4.   id   :: Int,
  5.   name :: String
  6. } deriving Show
  7.  
  8. type MyState = Int
  9. startState = 0
  10.  
  11. tick :: State MyState Int
  12. tick = do
  13.   n <- get
  14.   put (n+1)
  15.   return n
  16.  
  17. names = ["Adam","Barney","Charlie"]
  18.  
  19. (persons, lastId) = (`runState` startState) $ do
  20.    forM names $ \thisName -> do
  21.       newId <- tick
  22.       return $ Person newId thisName
  23.  
  24. main = print persons
Compilation error #stdin compilation error #stdout 0s 0KB
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stdin
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Standard input is empty
compilation info 
prog.hs:1:7:
    Could not find module `Control.Monad.State':
      Use -v to see a list of the files searched for.
stdout
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Standard output is empty
https://ideone.com/OLAZh
language:
Haskell (ghc 8.4.4)
created:
11 years ago
visibility:
public

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