From: Jim Pryor <profjim@jimpryor.net>
Date: Fri, 26 Nov 2010 18:11:37 +0000 (-0500)
Subject: ass7 hint5: add comment
X-Git-Url: http://lambda.jimpryor.net/git/gitweb.cgi?p=lambda.git;a=commitdiff_plain;h=ee78c002ea1d6c0ed2489ae5719c8f63e3ae1b3a

ass7 hint5: add comment

Signed-off-by: Jim Pryor <profjim@jimpryor.net>
---

diff --git a/hints/assignment_7_hint_5.mdwn b/hints/assignment_7_hint_5.mdwn
index acbc9015..779fb2ed 100644
--- a/hints/assignment_7_hint_5.mdwn
+++ b/hints/assignment_7_hint_5.mdwn
@@ -1,3 +1,15 @@
+<!--
+I would like to propose one pedegogical suggestion (due to Ken), which
+is to separate peg addition from non-determinacy by explicitly adding
+a "Let" construction to GSV's logic, i.e., "Let of var * term *
+clause", whose interpretation adds a peg, assigns var to it, sets the
+value to the value computed by term, and evaluates the clause with the
+new peg in place.  This can be added easily, especially since you have
+supplied a procedure that handles the main essence of the
+construction.  Once the Let is in place, adding the existential is
+purely dealing with nondeterminism.
+-->
+
 *	How shall we handle \[[&exist;x]]? As we said, GS&V really tell us how to interpret \[[&exist;xPx]], but for our purposes, what they say about this can be broken naturally into two pieces, such that we represent the update of our starting set `u` with \[[&exist;xPx]] as:
 
 	<pre><code>u >>= \[[&exist;x]] >>= \[[Px]]