memory leak

This simple test program leaks memory for no obvious reason.

module Main where

import Control.Monad
import Control.Monad.Trans.Reader

main :: IO ()
main = do
    runReaderT task ()
    main

task :: ReaderT () IO ()
task = forM_ [(1::Integer)..] $ \cnt -> do
    return cnt

However, there are some minor changes that (each individual change alone) make this program run in constant memory.

1. If I remove

module Main where

1. If I remove recursive call to main
2. If I put task definition under the scope of main, like so

module Main where

import Control.Monad
import Control.Monad.Trans.Reader

main :: IO ()
main = do
    runReaderT task ()
    main
  where
    task :: ReaderT () IO ()
    task = forM_ [(1::Integer)..] $ \cnt -> do
        return cnt

Any of the changes above make the program run OK, but I belive that this should be also true for the original test program. I am not sure where the problem is (if at all), but it's extremely difficult to isolate this kind of problem in the real application.

Please check if anything can be done on the compiler or runtime to prevent this kind of problems.

Trac metadata

Trac field	Value
Version	8.0.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
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