Merge branch 'system-reqs'

.requirements/ghc/default

@@ -0,0 +1 @@
+curl g++ gcc gmp make ncurses python3 realpath xz-utils

.requirements/ghc/ubuntu

@@ -0,0 +1 @@
+curl g++ gcc libgmp-dev libtinfo-dev make ncurses-dev python3 realpath xz-utils

bootstrap-haskell

@@ -33,10 +33,9 @@ echo "PATH components."
 echo
 
 if [ -z "${BOOTSTRAP_HASKELL_NONINTERACTIVE}" ] ; then
-	echo "To proceed with the installation press enter, to cancel press ctrl-c."
+	echo "To proceed with the ghcup installation press enter, to cancel press ctrl-c."
 	echo "Note that this script can be re-run at any given time."
 	echo
-
 	# Wait for user input to continue.
 	# shellcheck disable=SC2034
 	read -r answer </dev/tty
@@ -59,6 +58,22 @@ else
 	edo . "${GHCUP_INSTALL_BASE_PREFIX}"/.ghcup/env
 fi
 
+echo
+echo "To install and run GHC you need the following dependencies:"
+echo "  $(ghcup print-system-reqs)"
+echo
+
+if [ -z "${BOOTSTRAP_HASKELL_NONINTERACTIVE}" ] ; then
+	echo "You may want to install these now, then press enter to proceed"
+	echo "or press ctrl-c to abort."
+	echo "Installation may take a while."
+	echo
+
+	# Wait for user input to continue.
+	# shellcheck disable=SC2034
+	read -r answer </dev/tty
+fi
+
 edo ghcup install
 
 edo ghcup set
@@ -74,3 +89,6 @@ printf "\\033[0;35m%s\\033[0m\\n" ""
 
 
 )
+
+# vim: tabstop=4 shiftwidth=4 expandtab
+

ghcup

@@ -100,10 +100,10 @@ DOWNLOADER="curl"
 # Options passed to the download program.
 DOWNLOADER_OPTS="--fail -O"
 
-# @VARIABLE: SCRIPT_UPDATE_URL
+# @VARIABLE: DOWNLOADER_STDOUT_OPTS
 # @DESCRIPTION:
-# Location to update this script from.
+# Options passed to the download program when printing the content to stdout.
-SCRIPT_UPDATE_URL="https://raw.githubusercontent.com/haskell/ghcup/master/ghcup"
+DOWNLOADER_STDOUT_OPTS="--fail"
 
 # @VARIABLE: GHC_DOWNLOAD_BASEURL
 # @DESCRIPTION:
@@ -121,11 +121,21 @@ JOBS="1"
 # the script name.
 SOURCE="$0"
 
+# @VARIABLE: BASE_DOWNLOAD_URL
+# DESCRIPTION:
+# The base url for downloading stuff like meta files, requirements files etc.
+BASE_DOWNLOAD_URL="https://raw.githubusercontent.com/haskell/ghcup/master/"
+
+# @VARIABLE: SCRIPT_UPDATE_URL
+# @DESCRIPTION:
+# Location to update this script from.
+SCRIPT_UPDATE_URL="${BASE_DOWNLOAD_URL}/ghcup"
+
 # @VARIABLE: META_DOWNLOAD_URL
 # DESCRIPTION:
 # The url of the meta file for getting
 # download information for ghc/cabal-install etc.
-META_DOWNLOAD_URL="https://raw.githubusercontent.com/haskell/ghcup/master/.download-urls"
+META_DOWNLOAD_URL="${BASE_DOWNLOAD_URL}/.download-urls"
 
 # @VARIABLE: META_DOWNLOAD_FORMAT
 # DESCRIPTION:
@@ -138,7 +148,7 @@ META_DOWNLOAD_FORMAT="1"
 # DESCRIPTION:
 # The url of the meta file for getting
 # available versions for ghc/cabal-install etc.
-META_VERSION_URL="https://raw.githubusercontent.com/haskell/ghcup/master/.available-versions"
+META_VERSION_URL="${BASE_DOWNLOAD_URL}/.available-versions"
 
 # @VARIABLE: META_VERSION_FORMAT
 # DESCRIPTION:
@@ -192,6 +202,7 @@ SUBCOMMANDS:
     install-cabal      Install cabal-install
     debug-info         Print debug info (e.g. detected system/distro)
     changelog          Show the changelog of a GHC release (online)
+    print-system-reqs  Print an approximation of system requirements
 
 DISCUSSION:
     ghcup installs the Glasgow Haskell Compiler from the official
@@ -407,7 +418,7 @@ DISCUSSION:
 
 # @FUNCTION: changelog_usage
 # @DESCRIPTION:
-# Print the help message for 'ghcup set' to STDERR
+# Print the help message for 'ghcup changelog' to STDERR
 # and exit the script with status code 1.
 changelog_usage() {
     (>&2 echo "ghcup-changelog
@@ -431,6 +442,30 @@ DISCUSSION:
     exit 1
 }
 
+# @FUNCTION: print_system_reqs_usage
+# @DESCRIPTION:
+# Print the help message for 'ghcup print-system-reqs' to STDERR
+# and exit the script with status code 1.
+print_system_reqs_usage() {
+    (>&2 echo "ghcup-print-system-reqs
+Print an approximation of system requirements
+
+USAGE:
+    ${SCRIPT} print-system-reqs
+
+FLAGS:
+    -h, --help       Prints help information
+
+DISCUSSION:
+    Just prints an approximation of the system requirements
+    for the 'recommended' GHC version and the 'latest' distro version
+    you are on.
+
+    Review this output carefully!
+")
+    exit 1
+}
+
 
 
 
@@ -967,6 +1002,16 @@ download_silent() {
     fi
 }
 
+# @FUNCTION: download_to_stdout
+# @USAGE: <url>
+# @DESCRIPTION:
+# Downloads the given url to stdout.
+download_to_stdout() {
+    [ -z "$1" ] && die "Internal error: no argument given to download"
+    # shellcheck disable=SC2086
+    edo ${DOWNLOADER} ${DOWNLOADER_STDOUT_OPTS} "$1"
+}
+
 # @FUNCTION: unpack
 # @USAGE: <tarball>
 # @DESCRIPTION:
@@ -1807,6 +1852,42 @@ changelog() {
 }
 
 
+    ######################################
+    #--[ Subcommand print-system-reqs ]--#
+    ######################################
+
+
+# @FUNCTION: system_reqs_url
+# @USAGE: <distro-alias>
+# @DESCRIPTION:
+# Mapping of distro-alias to system requirements URL.
+system_reqs_url() {
+    [ -z "$1" ] && die "Internal error: no argument given to system_reqs_url"
+
+    case "$1" in
+    "debian"|"ubuntu")
+        printf "%s/.requirements/ghc/ubuntu" "${BASE_DOWNLOAD_URL}"
+        ;;
+    *)
+        printf "%s/.requirements/ghc/default" "${BASE_DOWNLOAD_URL}"
+        ;;
+    esac
+}
+
+
+# @FUNCTION: print_system_reqs
+# @DESCRIPTION:
+# Print the system requirements (approximation).
+print_system_reqs() {
+    mydistro=$(get_distro_alias "$(get_distro_name)")
+    reqs_url=$(system_reqs_url "${mydistro}")
+
+    download_to_stdout "${reqs_url}"
+
+    unset mydistro reqs_url
+}
+
+
 
 
     #######################
@@ -1848,6 +1929,7 @@ while [ $# -gt 0 ] ; do
     -w|--wget)
         DOWNLOADER="wget"
         DOWNLOADER_OPTS=""
+        DOWNLOADER_STDOUT_OPTS="-qO-"
         shift 1
         if [ $# -lt 1 ] ; then
             usage
@@ -2075,6 +2157,16 @@ while [ $# -gt 0 ] ; do
                fi
            fi
            break;;
+       print-system-reqs)
+           shift 1
+           while [ $# -gt 0 ] ; do
+               case $1 in
+                   -h|--help) print_system_reqs_usage;;
+                   *) print_system_reqs_usage;;
+               esac
+           done
+           print_system_reqs
+           break;;
        *) usage;;
        esac
        break;;