From b1238c98a1d4ac6f72e6651fc8d4c40d69452f1c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B8rn=20Erik=20Pedersen?=
 <bjorn.erik.pedersen@gmail.com>
Date: Mon, 17 Jul 2017 11:11:10 +0200
Subject: [PATCH] Document Pages support in union and intersect

Fixes #26
---
 content/functions/intersect.md | 13 +++++++++++++
 content/functions/union.md     | 13 +++++++++++++
 2 files changed, 26 insertions(+)

diff --git a/content/functions/intersect.md b/content/functions/intersect.md
index 5c1ffce97..fc56e9b93 100644
--- a/content/functions/intersect.md
+++ b/content/functions/intersect.md
@@ -41,5 +41,18 @@ The following is an example of a "related posts" [partial template][partials] th
 ```
 {{% /code %}}
 
+This is also very useful to use as `AND` filters when combined with where:
+
+```html
+{{ $pages := where .Site.RegularPages "Type" "not in" (slice "page" "about") }}
+{{ $pages := $pages | union (where .Site.RegularPages "Params.pinned" true) }}
+{{ $pages := $pages | intersect (where .Site.RegularPages "Params.images" "!=" nil) }}
+```
+
+The above fetches regular pages not of `page` or `about` type unless they are pinned. And finally, we exclude all pages with no `images` set in Page params.
+
+See [union](/functions/union) for `OR`.
+
+
 [partials]: /templates/partials/
 [single]: /templates/single-page-templates/
diff --git a/content/functions/union.md b/content/functions/union.md
index 8938a3728..7baf90592 100644
--- a/content/functions/union.md
+++ b/content/functions/union.md
@@ -34,3 +34,16 @@ Given two arrays (or slices) A and B, this function will return a new array that
 {{ union nil nil }}
 <!-- returns an error because both arrays/slices have to be of the same type -->
 ```
+
+
+This is also very useful to use as `AND` filters when combined with where:
+
+```html
+{{ $pages := where .Site.RegularPages "Type" "not in" (slice "page" "about") }}
+{{ $pages := $pages | union (where .Site.RegularPages "Params.pinned" true) }}
+{{ $pages := $pages | intersect (where .Site.RegularPages "Params.images" "!=" nil) }}
+```
+
+The above fetches regular pages not of `page` or `about` type unless they are pinned. And finally, we exclude all pages with no `images` set in Page params.
+
+See [intersect](/functions/intersect) for `AND`.