X-Git-Url: http://lambda.jimpryor.net/git/gitweb.cgi?p=lambda.git;a=blobdiff_plain;f=reader_monad_for_variable_binding.mdwn;h=b9fd816d439ee693e26d2ae9173264d856085651;hp=9ddddc8888847f02af94487e6edc47da1bc88e73;hb=7a822d410076318ea12be4e3cdb57e1b91218f42;hpb=3ef22cae11ec60126584496a6923b967510e70ad

diff --git a/reader_monad_for_variable_binding.mdwn b/reader_monad_for_variable_binding.mdwn
index 9ddddc88..b9fd816d 100644
--- a/reader_monad_for_variable_binding.mdwn
+++ b/reader_monad_for_variable_binding.mdwn
@@ -1,3 +1,5 @@
+[[!toc]]
+
 Substitution versus Environment-based Semantics
 -----------------------------------------------
 
@@ -155,7 +157,10 @@ Here we'll use a different monad. It's called the **Reader monad**. We define it
 
 	(* here's our bind operation; how does it work? *)
 	let bind (u : 'a reader) (f: 'a -> 'b reader) : 'b reader =
-		fun (e : env) -> f (u e) e
+		(* this can be written more compactly, but having it spelled out
+		   like this will be useful down the road *)
+		fun (e : env) -> let a = u e in let u' = f a in u' e
+
 
 	(* we also define two special-purpose operations on our reader-monad values *)