File: TH_recursiveDoImport.hs

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{-# LANGUAGE RecursiveDo #-}
{-# LANGUAGE TemplateHaskell #-}
module TH_recursiveDoImport where
import Data.IORef
import Language.Haskell.TH

data SelfRef = SelfRef (IORef (IORef SelfRef))

recIO :: ExpQ
recIO = [e|
    do rec r1 <- newIORef r2
           r2 <- newIORef (SelfRef r1)
       readIORef r2 |]

mdoIO :: ExpQ
mdoIO = [e|
    mdo r1 <- return r2
        r2 <- return (const 1 r1)
        return r1 |]

emptyRecIO :: ExpQ
emptyRecIO = [e|
   do rec {}
      return () |]