From 059059ac879423685e1aba6ad1e6ee487272bc49 Mon Sep 17 00:00:00 2001
From: Gaith Hallak <gaithhallak@gmail.com>
Date: Thu, 2 Sep 2021 13:02:18 +0300
Subject: [PATCH] Update docs

---
 docs/sophia_features.md | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/docs/sophia_features.md b/docs/sophia_features.md
index 263eb12..48e6c8a 100644
--- a/docs/sophia_features.md
+++ b/docs/sophia_features.md
@@ -121,7 +121,7 @@ contract IntHolder =
   type state = int
   entrypoint init(x) = x
   entrypoint get() = state
-  
+
 main contract IntHolderFactory =
   stateful entrypoint new(x : int) : IntHolder =
     let ih = Chain.create(x) : IntHolder
@@ -482,6 +482,25 @@ function g(p : int * option(int)) : int =
   b
 ```
 
+Guards are boolean functions that can be used on patterns in both switch
+statements and functions definitions:
+
+```sophia
+function get_left_if_positive(x : one_or_both('a, 'b)) : option('a) =
+  switch(x)
+    Left(x)    | x > 0 => Some(x)
+    Both(x, _) | x > 0 => Some(x)
+    _                  => None
+```
+
+```sophia
+function
+  get_left_if_positive : one_or_both('a, 'b) => option('a)
+  get_left(Left(x))    | x > 0 = Some(x)
+  get_left(Both(x, _)) | x > 0 = Some(x)
+  get_left(_)                  = None
+```
+
 *NOTE: Data types cannot currently be recursive.*
 
 ## Lists
@@ -851,4 +870,4 @@ Some chain operations (`Oracle.<operation>` and `AENS.<operation>`) have an
 optional delegation signature. This is typically used when a user/accounts
 would like to allow a contract to act on it's behalf. The exact data to be
 signed varies for the different operations, but in all cases you should prepend
-the signature data with the `network_id` (`ae_mainnet` for the æternity mainnet, etc.).
\ No newline at end of file
+the signature data with the `network_id` (`ae_mainnet` for the æternity mainnet, etc.).