From 412edce3a001233a308fd10c5c31ae52094e55e4 Mon Sep 17 00:00:00 2001 From: Jim Pryor Date: Thu, 18 Nov 2010 13:12:47 -0500 Subject: [PATCH 1/1] assignment7 tweaks Signed-off-by: Jim Pryor --- hints/assignment_7_hint_2.mdwn | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) 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. -- 2.11.0