Data.Map memory leaks after an inline

[nikivazou]

Hey, my program returns within seconds with the below function, but runs forever when the first occurrence of f1' is replaced with the equivalent f1 m.

import qualified Data.Map as M

combine :: (Ord k) => (M.Map k v -> [(k, v)]) -> (M.Map k v -> [(k, v)])
        -> (M.Map k v -> [(k, v)])
combine f1 f2 m =
  let f1' = f1 m
      f2' = f2 (m `M.union` M.fromList f1') -- program does not terminate when f1' is replace with f1 m 
  in f1' ++ f2'

Not sure if this expected or known, but I cannot explain it, so reporting it in case it's worth further investigation.

I am using containers-0.7 and ghc-9.10.1.

(@pacastega)

[meooow25]

Hi, that is certainly strange, but it's hard to figure something out without knowing the inputs to the function. Do you have a reproducible example?

[nikivazou]

Let's see if we can reproduce this behavior in a small file.
If not, if you are interested, we could give you access to the complete project that has this behavior.