diff --git a/zsh/.config/zsh/source/archlinux-contrib.zsh b/zsh/.config/zsh/source/archlinux-contrib.zsh
new file mode 100644
index 0000000..1709a39
--- /dev/null
+++ b/zsh/.config/zsh/source/archlinux-contrib.zsh
@@ -0,0 +1,27 @@
+#
+# helper functions for Arch Linux related work
+#
+
+# generates a deterministic hash of the current working directory
+# TODO expand hash algos to use makepkg's blessed algos
+# e.g hashdir $ALGO where ALGO=md5|sha1|sha224|sha256|sha384|sha512|b2
+# NB: i don't trust anything before sha256...
+function hashdir() {
+  find \
+    . \
+    -type f \
+    -not -path '*/\.git/*' \
+    -exec b2sum {} + | \
+    LC_ALL=C sort | \
+    b2sum | \
+    cut -d ' ' -f 1
+}
+
+# obtain commit hash for a specific reference/tag
+function tag2commit() {
+  local repository=$1
+  local tag=$2
+
+  git ls-remote $repository $tag
+}
+# vim: ft=zsh expandtab tabstop=2 shiftwidth=2