X-Git-Url: http://lambda.jimpryor.net/git/gitweb.cgi?p=lambda.git;a=blobdiff_plain;f=hints%2Fassignment_7_hint_2.mdwn;h=3a3accae5cb1e99155654ed756660dfee19c6b00;hp=d79f064c04b0a029ff6ef27689c1758c6470b534;hb=f13c3904992a39aa33db9c1c80a4a984dabc341b;hpb=2d5df0441175013c782ebee648a17043405ca251

diff --git a/hints/assignment_7_hint_2.mdwn b/hints/assignment_7_hint_2.mdwn
index d79f064c..3a3accae 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.
 
@@ -24,7 +24,7 @@
 		let bind_set (u: 'a set) (f: 'a -> 'b set) =
 			List.concat (List.map f u);;
 
-*	So GS&V's information states, which they notate using `s`, are set-monads, whose elements in turn are discourse possibilities, which they notate using `i`, which are state monads that keep track of which entities have been introduced as objects of discourse, and which variables are bound to them, in a given discourse possibility.
+*	So GS&V's information states, which they notate using `s`, are set-monads, whose elements in turn are discourse possibilities, which they notate using `i`, which are state monads that keep track of which entities have been introduced as objects of discourse, and which variables are bound to them, in a given discourse possibility. In GS&V's system, possibilities are triples of an assignment function, `r`, a store `g`, and a world `w`. We're leaving the worlds out. Also, instead of just working with pairs `(r, g)`, we're working with state monads for which those pairs constitute the states we update.
 
 
 *	[More hints](/hints/assignment_7_hint_3).