HEADS UP: Running cabal install with the latest GHC

Edward Z. Yang ezyang at mit.edu
Fri Aug 8 12:00:37 UTC 2014

Hey all,

SPJ pointed out to me today that if you try to run:

    cabal install --with-ghc=/path/to/inplace/bin/ghc-stage2

with the latest GHC HEAD, this probably will not actually work, because
your system installed version of Cabal is probably too old to deal with
the new package key stuff in HEAD.  So, how do you get a version
of cabal-install (and Cabal) which is new enough to do what you need
it to?

The trick is to compile Cabal using your /old/ GHC. Step-by-step, this
involves cd'ing into libraries/Cabal/Cabal and running `cabal install`
(or install it in a sandbox, if you like) and then cd'ing to
libraries/Cabal/cabal-install and cabal install'ing that.

Cabal devs, is cutting a new release of Cabal and cabal-install in the
near future possible? In that case, users can just cabal update; cabal
install cabal-install and get a version of Cabal which will work for


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