Thanks to some intrepid sleuthing by Albert Y. C. Lai, we realized there was a serious problem in the full (not core) builds of HP for Mac and Linux (not Windows). If you've seen lots of "unusable due to shadowed dependencies" errors on packages that came with full 8.2.1 platform installs on those systems, this is likely why. We should have tested better and caught this, and I'm sorry for the trouble it has caused. I've released a new build of the full mac installer, and updated the hash on the site. A new generic-linux build should follow soon. Regards, Gershom P.s. For those interested, the technical details are at https://github.com/haskell/haskell-platform/issues/285 -- in brief, the platform had done builds using inplace conf files but deployed using proper target package-conf files. This worked just fine until the new abi-depends machinery was introduced for better computing dependency mismatches (https://phabricator.haskell.org/D2846 is one place to start reading about that). That new machinery then recognized that different abis were generated for the inplace conf than the target conf, and things went screwy. But the problem here isn't with those changes -- it's with our inadequate testing that should have caught when things went wrong and alerted us that we needed to step back and fix things earlier, and the responsibility for that is all on me.