diff --git a/zsh/.config/zsh/source/archlinux-contrib.zsh b/zsh/.config/zsh/source/archlinux-contrib.zsh
index 1709a39..01b88ef 100644
--- a/zsh/.config/zsh/source/archlinux-contrib.zsh
+++ b/zsh/.config/zsh/source/archlinux-contrib.zsh
@@ -24,4 +24,49 @@ function tag2commit() {
 
   git ls-remote $repository $tag
 }
+
+# wrapper around extra-x86_64-build for caching downloaded dependencies
+# TODO expand to use testing/staging
+function ab-extra() {
+  local EXTRA_ARGS=()
+
+  # capture output for parsing dependencies
+  makepkg_output=$(makepkg --printsrcinfo)
+
+  #
+  # cache various downloads
+  #
+  # rust - crates
+  if grep -q "depends = rust\|cargo" <<<"$makepkg_output"; then
+    EXTRA_ARGS+=(
+      -d /var/cache/cargo/git:/build/.cargo/git
+      -d /var/cache/cargo/registry:/build/.cargo/registry
+    )
+  fi
+
+  # go - modules
+  if grep -q "depends = go" <<<"$makepkg_output"; then
+    EXTRA_ARGS+=(
+      -d /var/cache/golang/pkg:/build/go/pkg
+      -d /var/cache/golang/build:/build/.cache/go-build
+    )
+  fi
+
+  # dart - packages
+  if grep -q "depends = dart" <<<"$makepkg_output"; then
+    EXTRA_ARGS+=(-d /var/cache/dartlang:/build/.pub-cache)
+  fi
+
+  # javascript - npm/yarn/pkg
+  if grep -q "depends = npm\|yarn\|nodejs" <<<"$makepkg_output"; then
+    EXTRA_ARGS+=(
+      -d /var/cache/javascript/npm:/build/.npm
+      -d /var/cache/javascript/pkg-cache:/build/.pkg-cache
+      -d /var/cache/javascript/yarn:/build/.cache/yarn
+    )
+  fi
+
+  extra-x86_64-build -- ${EXTRA_ARGS[@]} ${@}
+}
+
 # vim: ft=zsh expandtab tabstop=2 shiftwidth=2