[Haskell-cafe] Switching GHC Version

[Sean Leather]

Hi Yusaku,

On Tue, Feb 7, 2012 at 00:27, HASHIMOTO, Yusaku wrote:

> Hi, I wrote a simple shell function for switching GHC version on the
> system. It works only under Mac OSX, and only switch GHCs installed
> via .pkg installers. It's useful to experiment newer features without
> worrying breaking environment.
>
> GHC_BASE_DIR=/Library/Frameworks/GHC.framework/Versions/
>
> ghcs () {
>  VERSION=$1
>  sudo $GHC_BASE_DIR/$VERSION/Tools/create-links . /Library/Frameworks /
> }
>

I have something quite similar, though mine depends on just one symbolic
link, "Current". See the end of this email.

This approach also works with GHC installed from source. I use the
following script to run 'configure' in the GHC source:

$ cat configure.mine
VERSION=7.4.1
./configure \
  --prefix=/Library/Frameworks/GHC.framework/Versions/$VERSION/usr   \
  --with-gmp-libraries=/Library/Frameworks/GMP.framework                \
  --with-gmp-includes=/Library/Frameworks/GMP.framework/Headers

For me, the 'ghc-ver' script is useful since I'm often just want to quickly
play with something in one version of GHC and not create a development
environment. Other tools and approaches that have already been mentioned
are also useful.

Regards,
Sean

----

$ cat ~/bin/ghc-ver
#!/bin/sh

ECHO="/bin/echo"

PROGNAME=`basename $0`

if [ -z "$1" ];
then
  $ECHO "Usage: $PROGNAME <version>"
  $ECHO "       $PROGNAME list"
  exit 1
fi

VERSIONS_DIR="/Library/Frameworks/GHC.framework/Versions"

if [ "$1" = "list" ];
then
  /usr/bin/find $VERSIONS_DIR -type d -depth 1 | xargs basename
  exit 0
fi

CHOSEN_DIR="$VERSIONS_DIR/$1"

$ECHO -n "Checking for $CHOSEN_DIR ... "

if [ -d "$CHOSEN_DIR" ];
then
  rm $VERSIONS_DIR/Current
  ln -sf $CHOSEN_DIR $VERSIONS_DIR/Current
  $ECHO "Success!"
else
  $ECHO "Not found!"
fi

ghc --version

$ ls -l /usr/bin/ghc # as well as ghci, ghc-pkg, etc.
lrwxr-xr-x  [...] /usr/bin/ghc ->
/Library/Frameworks/GHC.framework/Versions/Current/usr/bin/ghc
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