Git post-merge hook to auto-install dependencies

_helpers.sh

#!/usr/bin/env bash
set -euo pipefail
IFS=$'\n\t'

changed_files="$(git diff-tree -r --name-only --no-commit-id ORIG_HEAD HEAD)"

on_changed() {
  echo "$changed_files" | grep --quiet "$1" && eval "$2" || return 0
}

post-merge.sh

#!/usr/bin/env bash
set -euo pipefail
IFS=$'\n\t'

source _helpers.sh

on_changed 'yarn.lock' 'yarn'
on_changed 'package-lock.json' 'npm install'