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Comment by exceptione | Hacker News Reader

In my opinion, Haskell Platform (HP) gets updates too slowly. I understand that the purpose is to have a coherent set of compatible packages, but in my opinion there should be a minor HP release for every ghc update in between. The fixes and improvements in ghc range from usefull to nessecary. It should be possible to release minor hp updates with the automated test suite.

As a HP user, the wait for ghc-7.6 to be incorporated has been too long imho.

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If you are an HP user because you want stability, then the wait for ghc-7.6 was just long enough: There was a critical bug fixed in 7.6.3 which was released just in time for this HP release!

We do not release HP for every GHC update for two reasons: 1) Most GHC updates are not in the stability category that HP strives for, 2) Often new GHCs require minor updates to other packages in the HP. The revving of the whole kaboodle more than twice a year is far too much work than the small volunteer group can handle!

What stopped you from installing ghc-7.6 yourself? I've been using 7.4 (from Platform) and 7.6 in parallel for over half a year without problem.

ok! Well I was terrified by the big fat warnings that doing so might break your packages randomly.

Easy workaround—use `hsenv --ghc=ghc-X.X.tar.gz --name head` to build an isolated hsenv that uses whichever version of GHC you like. You then activate it with `source .hsenv_head/bin/activate`.

GHC uses a per-version package database, so that should never be possible for different GHC versions. For example, I have the 7.4 from platform installed in /usr/bin/ghc (the normal location for Platform installs on OSX) and 7.7 installed in ~/ghc.

Switching between the two versions is as easy as making sure that ~/ghc/bin is on my path before /usr/bin/ghc. All I need to do is "export PATH=~/ghc/bin:$PATH" and things work. Packages get installed in either ~/Library/Haskell/ghc-7.4.1 or ~/Library/Haskell/ghc-7.7 depending on what's in my path when I run "cabal install".

Ah thanks, did not know that! I'm on Windows but switching paths should be possible on Windows as well. :)

Don't try ghc-7.7. After -fdefer-type-errors and -XTypeHoles there is no way back.

If I recall, defer-type-errors is in 7.6, too

Yep, thanks. But those nifty type holes…

I haven't used them, but the day there's Agda in my haskell will be a good day.

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