how about ~/.cabal/store/ ?

[juhp]

Have you considered extending to allow also cleaning ~/.cabal/store/ ?

Or is there any other tool for that - other than a filemanager (but it can be error-prone)?

[andreasabel]

The problem with removing from ˜/.cabal/store is that one might have installed binaries using cabal which point back to the store. Deleting from the store will make these executables dysfunctional.

There were rumors about a GSoC project to implement garbage collection for cabal build products, but I don't know whether it has happened or will happen.
CC @fgaz

[fgaz]

The upstream ticket is haskell/cabal#3333.

In the end the GSoC project wasn't picked up.

There are a few third party tools, such as https://github.com/phadej/cabal-extras/tree/master/cabal-store-gc