Multiple versions of happy
Simon Peyton Jones
simonpj at microsoft.com
Tue Mar 30 13:16:59 UTC 2021
What's the approved mechanism to install multiple versions of happy/alex etc? Eg I tried to build ghc-9.0 and got this:
checking for makeinfo... no
checking for python3... /usr/bin/python3
checking for ghc-pkg matching /opt/ghc/bin/ghc... /opt/ghc/bin/ghc-pkg
checking for happy... /home/simonpj/.cabal/bin/happy
checking for version of happy... 1.20.0
configure: error: Happy version 1.19 is required to compile GHC.
I so I have to
1. Install happy-1.19 without overwriting the installed happy-1.20
2. Tell configure to use happy-1.19
What's the best way to do those two things?
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