commit 799067f9d7045d3b90ce7da284145ca24c6c2100
Author: Julian Ospald <hasufell@posteo.de>
Date:   Sat Sep 29 15:50:26 2018 +0800

    Initial commit

diff --git a/ghcup.sh b/ghcup.sh
new file mode 100755
index 0000000..6bb56ba
--- /dev/null
+++ b/ghcup.sh
@@ -0,0 +1,222 @@
+#!/bin/sh
+
+set -e
+
+## global variables ##
+
+VERSION=0.0.1
+SCRIPT="$(basename $0)"
+VERBOSE=false
+
+
+## print help ##
+
+usage() {
+    (>&2 echo "${SCRIPT} [FLAGS] <SUBCOMMAND>
+
+FLAGS:
+    -v, --verbose    Enable verbose output
+    -h, --help       Prints help information
+    -V, --version    Prints version information
+
+SUBCOMMANDS:
+    install          Update Rust toolchains and rustup
+")
+    exit 1
+}
+
+install_usage() {
+    (>&2 echo "${SCRIPT} install [FLAGS] <VERSION>
+
+FLAGS:
+    -h, --help       Prints help information
+
+ARGS:
+    <VERSION>        E.g. \"8.4.3\" or \"8.6.1\"
+")
+    exit 1
+}
+
+
+## utilities ##
+
+die() {
+    (>&2 echo "$1")
+    exit 2
+}
+
+if_verbose() {
+    if ${VERBOSE} ; then
+        printf "$1"
+    else
+        [ -n "$2" ] && printf "$2"
+    fi
+}
+
+echov() {
+    if ${VERBOSE} ; then
+        echo "$1"
+    fi
+}
+
+get_distro_name() {
+    if [ -f /etc/os-release ]; then
+        # freedesktop.org and systemd
+        . /etc/os-release
+        printf "$NAME"
+    elif type lsb_release >/dev/null 2>&1; then
+        # linuxbase.org
+        printf "$(lsb_release -si)"
+    elif [ -f /etc/lsb-release ]; then
+        # For some versions of Debian/Ubuntu without lsb_release command
+        . /etc/lsb-release
+        printf "$DISTRIB_ID"
+    elif [ -f /etc/debian_version ]; then
+        # Older Debian/Ubuntu/etc.
+        printf "Debian"
+    else
+        # Fall back to uname, e.g. "Linux <version>", also works for BSD, etc.
+        printf "$(uname -s)"
+    fi
+}
+
+get_distro_ver() {
+    if [ -f /etc/os-release ]; then
+        # freedesktop.org and systemd
+        . /etc/os-release
+        printf "$VERSION_ID"
+    elif type lsb_release >/dev/null 2>&1; then
+        # linuxbase.org
+        printf "$(lsb_release -sr)"
+    elif [ -f /etc/lsb-release ]; then
+        # For some versions of Debian/Ubuntu without lsb_release command
+        . /etc/lsb-release
+        printf "$DISTRIB_RELEASE"
+    elif [ -f /etc/debian_version ]; then
+        # Older Debian/Ubuntu/etc.
+        printf "$(cat /etc/debian_version)"
+    else
+        # Fall back to uname, e.g. "Linux <version>", also works for BSD, etc.
+        printf "$(uname -r)"
+    fi
+}
+
+
+get_arch() {
+    myarch=$(uname -m)
+
+    case "${myarch}" in
+    x86_64)
+        printf "x86_64"  # or AMD64 or Intel64 or whatever
+        ;;
+    i*86)
+        printf "i386"  # or IA32 or Intel32 or whatever
+        ;;
+    *)
+        die "Cannot figure out architecture (was: ${myarch})"
+        ;;
+    esac
+
+    unset myarch
+}
+
+get_download_url() {
+    myghcver=$1
+    myarch=$(get_arch)
+    mydistro=$(get_distro_name)
+    mydistrover=$(get_distro_ver)
+    baseurl="https://downloads.haskell.org/~ghc"
+
+    case "${mydistro},${mydistrover},${myarch},${myghcver}" in
+    Debian,7,i386,8.2.2)
+        printf "${baseurl}/${myghcver}/ghc-${myghcver}-${myarch}-deb${mydistrover}-linux.tar.xz"
+        break;;
+    *,*,i386,*)
+        printf "${baseurl}/${myghcver}/ghc-${myghcver}-${myarch}-deb8-linux.tar.xz"
+        break;;
+    Debian,8,*,*)
+        printf "${baseurl}/${myghcver}/ghc-${myghcver}-${myarch}-deb8-linux.tar.xz"
+        break;;
+    Debian,*,*,*)
+        printf "${baseurl}/${myghcver}/ghc-${myghcver}-${myarch}-deb9-linux.tar.xz"
+        break;;
+    Ubuntu,*,*,*)
+        printf "${baseurl}/${myghcver}/ghc-${myghcver}-${myarch}-deb9-linux.tar.xz"
+        break;;
+    *,*,*,*) # this is our best guess
+        printf "${baseurl}/${myghcver}/ghc-${myghcver}-${myarch}-fedora27-linux.tar.xz"
+        break;;
+    esac
+
+    unset myghcver myarch mydistro mydistrover baseurl
+}
+
+
+## subcommand install ##
+
+install_ghc() {
+    myghcver=$1
+    downloader=curl
+    downloader_opts="$(if_verbose "-v") -O"
+    old_pwd=${PWD}
+    inst_location=$HOME/.ghcup/${myghcver}
+
+    echov "Installing ghc for $(get_distro_name) on architecture $(get_arch)"
+
+    cd "$(mktemp -d)"
+
+    echov "Downloading $(get_download_url ${myghcver})"
+    ${downloader} ${downloader_opts} "$(get_download_url ${myghcver})"
+
+    tar $(if_verbose "-v") -xf ghc-*-linux.tar.xz
+    cd ghc-${myghcver}
+
+    if [ -z "$HOME" ] ; then
+        die "HOME env not set, cannot install GHC"
+    else
+        echov "Installing GHC into ${inst_location}"
+    fi
+
+    ./configure --prefix="${inst_location}"
+    make install
+
+    cd "${old_pwd}"
+
+    echo "Done installing, set up your current GHC via: ${SCRIPT} set-ghc ${myghcver}"
+
+    unset myghcver downloader downloader_opts old_pwd inst_location
+}
+
+
+
+## command line parsing and entry point ##
+
+while [ $# -gt 0 ] ; do
+    case $1 in
+    -v|--verbose)
+        VERBOSE=true
+        shift 1;;
+    -V|--version)
+        printf "${VERSION}"
+        exit 0;;
+    -h|--help)
+        usage;;
+    *) case $1 in
+       install)
+           shift 1
+           while [ $# -gt 0 ] ; do
+               case $1 in
+                   -h|--help) install_usage;;
+                   *) GHC_VER=$1
+                      break;;
+               esac
+           done
+           [ "${GHC_VER}" ] || install_usage
+           install_ghc ${GHC_VER}
+           break;;
+       *) usage;;
+       esac
+       break;;
+    esac
+done
+