[gitlab ci] add deps stage

.gitlab-ci.yml

@@ -13,15 +13,26 @@ variables:
   #- apt-get install make xz-utils
 
 stages:
+  - deps
   - test
 
+deps:
+  cache:
+  paths:
+    - node_modules/
+  script:
+    - nix-env -i purescript-0.14.4 -f https://github.com/NixOS/nixpkgs/archive/bed08131cd29a85f19716d9351940bdc34834492.tar.gz
+    - nix-env -i git
+    - nix-env -i nodejs
+    - nix-env -i yarn
+    - yarn --skip-builds
+
 test:
   cache:
     # cache per branch name
     # key: ${CI_COMMIT_REF_SLUG}
-    # paths:
-    #   - .stack-root/
-    #   - .stack-work/
+    paths:
+      - node_modules/
   script:
     # find 0.14.2 purescript version here:
     # https://lazamar.co.uk/nix-versions/