From: Jim Pryor
Date: Thu, 18 Nov 2010 18:12:47 +0000 (-0500)
Subject: assignment7 tweaks
X-Git-Url: http://lambda.jimpryor.net/git/gitweb.cgi?p=lambda.git;a=commitdiff_plain;h=412edce3a001233a308fd10c5c31ae52094e55e4
assignment7 tweaks
Signed-off-by: Jim Pryor
---
diff --git a/hints/assignment_7_hint_2.mdwn b/hints/assignment_7_hint_2.mdwn
index d79f064c..818d603e 100644
--- a/hints/assignment_7_hint_2.mdwn
+++ b/hints/assignment_7_hint_2.mdwn
@@ -1,5 +1,5 @@
-* GS&V's semantics involves elements from several different monads we've been looking at. First, they're working with (epistemic) modalities, so there are worlds playing a role like they did in [[Reader Monad for Intensionality]]. But we're going to ignore the modal element for this exercise. There's also variable binding, which is another reader monad. Next, there is a notion of a store, which some operations add new reference cells to. We implement this with a state monad (and so too do they, in effect, though they don't conceive of what they're doing in those terms). So we'll be working with a combination of both a reader monad for the variable binding and a state monad to keep track of the new "pegs" or reference cells.
+* GS&V's semantics involves elements from several different monads we've been looking at. First, they're working with (epistemic) modalities, so there are worlds playing a role like they did in [[Reader Monad for Intensionality]]. But we're going to ignore the modal element for this exercise. There's also variable binding, which is [another reader monad](/reader_monad_for_variable_binding). Next, there is a notion of a store, which some operations add new reference cells to. We implement this with a state monad (and so too do they, in effect, though they don't conceive of what they're doing in those terms). So we'll be working with a combination of both a reader monad for the variable binding and a state monad to keep track of the new "pegs" or reference cells.
There are systematic ways to layer different monads together. If you want to read about these, a keyword is "monad transformers." Ken Shan discusses them in [his paper](http://arxiv.org/abs/cs/0205026v1) that we recommended earlier.