Installing Multiple GHC Versions

multi-ghc.md

Installing Multiple GHC Versions

Use these instructions if you want to run multiple versions of GHC side-by-side.

This setup doesn't have GHC on the PATH by default, and uses g to cycle between available versions.

Install GHC 7.8.4

$ wget https://www.haskell.org/ghc/dist/7.8.4/ghc-7.8.4-x86_64-apple-darwin.tar.xz
$ tar xf ghc-7.8.4-x86_64-apple-darwin.tar.xz
$ cd ghc-7.8.4
$ ./configure --prefix=$HOME/haskell/ghc-7.8.4
$ make install

Install GHC 7.10.2

$ wget http://downloads.haskell.org/~ghc/7.10.2/ghc-7.10.2-x86_64-apple-darwin.tar.xz
$ tar xf ghc-7.10.2-x86_64-apple-darwin.tar.xz
$ cd ghc-7.10.2
$ ./configure --prefix=$HOME/haskell/ghc-7.10.2
$ make install

Zsh

Add the following to your .zshrc:

# List available GHC versions
ghc-list-available() {
  echo "Available versions:"
  for ver in $HOME/haskell/ghc-*; do
    echo "  ${ver##$HOME/haskell/ghc-}"
  done
}

# Switch to a specific GHC version
ghc-switch() {
  if [ -z "$1" ]; then
    echo "USAGE: ghc-switch VERSION"
    ghc-list-available
    return 1
  fi

  VER_PATH="$HOME/haskell/ghc-$1"
  if [ -d "$VER_PATH" ]; then
    export path=($VER_PATH/bin ${(@)path:#*ghc*})
    export GHC_VERSION=$1
    ghc --version
  else
    echo "GHC $1 isn't available"
    ghc-list-available
    return 1
  fi
}

# Cycle GHC versions
g() {
  case $GHC_VERSION in
    7.8.4)
      ghc-switch 7.10.2
      ;;
    *)
      ghc-switch 7.8.4
      ;;
  esac
}