Re: simultaneous ghc versions

On 2015-07-31 at 20:32:43 +0200, Evan Laforge wrote:

On Fri, Jul 31, 2015 at 11:26 AM, Herbert Valerio Riedel wrote:

...

Btw, I simply prepend to the $PATH env variable, or pass the appropriate executable name to `cabal`'s

-w --with-compiler=PATH give the path to a particular compiler

I don't understand, aren't they all in /usr/local/bin? Or do you use a version-specific prefix when installing each ghc version?

Sorry, I assumed this w/o saying; I maintain and use myself https://github.com/hvr/multi-ghc-travis which in fact uses version-specific install prefixes, resulting in the `bin` folder being /opt/ghc/<version>/bin

Also, ghc is not just the compiler, but also hsc2hs hpc runghc ghci ghc-pkg haddock-ghc. At the least, ghc-pkg has to be the right version,

`cabal` is actually clever enough to locate the appropriate executable, if I pass it a specific ghc executable (iirc it looks in the same folder where `ghc` was found) $ which ghc-pkg /opt/ghc/7.10.2/bin/ghc-pkg $ which hsc2hs /opt/ghc/7.10.2/bin/hsc2hs $ cabal configure -w /opt/ghc/7.6.3/bin/ghc -v2 ... Using ghc version 7.6.3 given by user at: /opt/ghc/7.6.3/bin/ghc Using ghc-pkg version 7.6.3 found on system at: /opt/ghc/7.6.3/bin/ghc-pkg Using hsc2hs version 0.67 found on system at: /opt/ghc/7.6.3/bin/hsc2hs ...

but all of those are version specific since they'll break if you remove their /usr/lib/ghc-version.