From 063c22f99e0cacb54e0026057bfacdecbc34d394 Mon Sep 17 00:00:00 2001
From: jim
Date: Mon, 23 Feb 2015 13:32:22 -0500
Subject: [PATCH] add
---
topics/week2_encodings.mdwn | 1 +
1 file changed, 1 insertion(+)
diff --git a/topics/week2_encodings.mdwn b/topics/week2_encodings.mdwn
index 85d4d77b..091fb4c5 100644
--- a/topics/week2_encodings.mdwn
+++ b/topics/week2_encodings.mdwn
@@ -231,6 +231,7 @@ That will evaluate to whatever this does:
f (f (f (z, 10), 20), 30)
+
With a commutative operator like `(+)`, it makes no difference whether you say `fold_right ((+), z) xs` or `fold_left ((+), z) xs`. But with other operators it will make a difference. We can't say `fold_left ((&), []) [10, 20, 30]`, since that would start by trying to evaluate `[] & 10`, which would crash. But we could do this:
let
--
2.11.0