From 629ad2e0971efcf58934c76ea1306b0ff0629339 Mon Sep 17 00:00:00 2001
From: Brujo Benavides
Date: Wed, 8 Aug 2018 12:51:59 -0300
Subject: Add clarification on nil type
As explained by @psyeugenic on Slack:
> empty list `[]` is regarded as a separate type from `list()`, `[]` < `list()`
> i.e. nil is `[]`
---
system/doc/reference_manual/expressions.xml | 4 ++++
1 file changed, 4 insertions(+)
(limited to 'system/doc/reference_manual')
diff --git a/system/doc/reference_manual/expressions.xml b/system/doc/reference_manual/expressions.xml
index 94e40dd077..684a1191d0 100644
--- a/system/doc/reference_manual/expressions.xml
+++ b/system/doc/reference_manual/expressions.xml
@@ -567,6 +567,10 @@ Expr1 op Expr2
order is defined:
number < atom < reference < fun < port < pid < tuple < map < nil < list < bit string
+
nil in the previous expression represents the empty list
+ (i.e. []), which is regarded as a separate type from
+ list/0. That's why nil < list.
+
Lists are compared element by element. Tuples are ordered by
size, two tuples with the same size are compared element by
element.