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chowells79 / lrucache

A simple pure LRU cache written in Haskell

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`insertInforming` is not working correctly

mohsen3 opened this issue · comments

commented

Running the following in ghci:

import Data.Cache.LRU
let l0 = newLRU (Just 2) :: LRU Int Int
let (l1, d1) = insertInforming 1 1 l0
let (l2, d2) = insertInforming 2 2 l1
let (l3, d3) = insertInforming 3 3 l2
print [(l1, d1), (l2, d2), (l3, d3)]

Results in:

[(fromList [(1,1)],Nothing),(fromList [(2,2),(1,1)],Nothing),(fromList [(3,3),(2,2)],Just (3,3))]

d3 should be Just (1, 1) rather than Just (3, 3). It seems that insertInforming is returning the input as the dropped element when the cache is full, while it is supposed to return the dropped out element. See https://github.com/chowells79/lrucache/blob/master/src/Data/Cache/LRU/Internal.hs#L146

In the case cache is not full, it is working fine.
Additionally, the IO module, do not expose an insertInforming function. I can create a PR for these changes if you are willing to merge it.

commented

Any updates on this? This is a serious bug which basically makes it impossible to use insertInforming.

commented

Sorry, I was badly burned out for a while. afd05d6 fixes this. New release coming soon.