installer support --nix parameter to be able running stack in nix-shell (#285)

* installer support --nix parameter to be able running stack in nix-shell

* add to readme: Installing in Nix build environment

Author: p-alik

README.md

@@ -399,6 +399,13 @@ to install from your clone:
 install.sh --repo CLONE-PATH
 ```
 
+### Installing in Nix build environment
+
+Use `--nix` parameter, in case you want to execute [stack installation in nix-shell](https://docs.haskellstack.org/en/stable/nix_integration/#use-stack-as-normal)
+```sh
+bash <(curl -sL https://git.io/haskell-vim-now) --nix
+```
+
 ## Troubleshooting
 
 See this [wiki](https://github.com/begriffs/haskell-vim-now/wiki/Installation-Troubleshooting)

install.sh

@@ -6,6 +6,7 @@ DEFAULT_BRANCH="master"
 DEFAULT_GENERATE_HOOGLE_DB=true
 DEFAULT_HVN_FULL_INSTALL=true
 DEFAULT_DRY_RUN=false
+DEFAULT_NIX=false
 
 if which tput >/dev/null 2>&1; then
     ncolors=$(tput colors)
@@ -111,6 +112,7 @@ do_setup() {
   local FULL_INSTALL=$2
   local GENERATE_HOOGLE_DB=$3
   local DRY_RUN=$4
+  local NIX=$5
   local setup_path=${HVN_DEST}/scripts/setup.sh
   local setup_haskell_path=${HVN_DEST}/scripts/setup_haskell.hs
 
@@ -127,6 +129,7 @@ do_setup() {
   then
     local ARG_NO_HOOGLE_DB="--no-hoogle"
     local ARG_NO_HELPER_BINS="--no-helper-bins"
+    local ARG_NIX=
 
     if [ "$GENERATE_HOOGLE_DB" == true ]
     then
@@ -149,7 +152,12 @@ do_setup() {
       exit_err "Detected stack version \"${STACK_VER}\", however version 1.4.0 or later is required."
     fi
 
-    stack $setup_haskell_path $ARG_NO_HOOGLE_DB $ARG_NO_HELPER_BINS ; RETCODE=$?
+    if [ "$NIX" == true ]
+    then
+      ARG_NIX="--nix"
+    fi
+
+    stack $ARG_NIX $setup_haskell_path $ARG_NO_HOOGLE_DB $ARG_NO_HELPER_BINS ; RETCODE=$?
     [ ${RETCODE} -ne 0 ] && exit_err "setup_haskell.hs failed with error ${RETCODE}."
   fi
 
@@ -162,11 +170,12 @@ main() {
   local FULL_INSTALL=$3
   local GENERATE_HOOGLE_DB=$4
   local DRY_RUN=$5
+  local NIX=$6
   local HVN_DEST="$(config_home)/haskell-vim-now"
   local HVN_DEPENDENCIES_DEST="$(config_home)/haskell-vim-now"
 
   install $REPO_PATH $REPO_BRANCH $HVN_DEST
-  do_setup $HVN_DEST $FULL_INSTALL $GENERATE_HOOGLE_DB $DRY_RUN
+  do_setup $HVN_DEST $FULL_INSTALL $GENERATE_HOOGLE_DB $DRY_RUN $NIX
 }
 
 function usage() {
@@ -181,6 +190,8 @@ function usage() {
   echo "           Disable Hoogle database generation. The default is $DEFAULT_GENERATE_HOOGLE_DB."
   echo "       --dry-run"
   echo "           Perform a dry run for the stack installs.  Primarily intended for testing."
+  echo "       --nix"
+  echo "           Perform stack build in a nix-shell. For more information see https://docs.haskellstack.org/en/stable/nix_integration"
   exit 1
 }
 
@@ -190,6 +201,7 @@ HVN_BRANCH=${HVN_BRANCH:=$DEFAULT_BRANCH}
 HVN_GENERATE_HOOGLE_DB=${HVN_GENERATE_HOOGLE_DB:=$DEFAULT_GENERATE_HOOGLE_DB}
 HVN_FULL_INSTALL=${HVN_FULL_INSTALL:=$DEFAULT_HVN_FULL_INSTALL}
 HVN_DRY_RUN=${HVN_DRY_RUN:=$DEFAULT_DRY_RUN}
+HVN_NIX=${HVN_NIX:=$DEFAULT_NIX}
 
 while test -n "$1"
 do
@@ -199,9 +211,10 @@ do
     --branch) shift; HVN_BRANCH=$1; shift; continue;;
     --no-hoogle) shift; HVN_GENERATE_HOOGLE_DB=false; continue;;
     --dry-run) shift; HVN_DRY_RUN=true; continue;;
+    --nix) shift; HVN_NIX=true; continue;;
     *) usage;;
   esac
 done
 
 test -n "$HVN_REPO" || usage
-main $HVN_REPO $HVN_BRANCH $HVN_FULL_INSTALL $HVN_GENERATE_HOOGLE_DB $HVN_DRY_RUN
+main $HVN_REPO $HVN_BRANCH $HVN_FULL_INSTALL $HVN_GENERATE_HOOGLE_DB $HVN_DRY_RUN $HVN_NIX