# HG changeset patch
# User Christian Urban <urbanc@in.tum.de>
# Date 1327158964 0
# Node ID d770a7b31aeb00ef208117296a98eb20b6a118d8
# Parent  2862dacb04aa39cc41a6d9ea8bca0a23bc89f1f2
modified the passage on beta-contractions

diff -r 2862dacb04aa -r d770a7b31aeb ProgTutorial/Essential.thy
--- a/ProgTutorial/Essential.thy	Wed Nov 30 13:35:10 2011 +0000
+++ b/ProgTutorial/Essential.thy	Sat Jan 21 15:16:04 2012 +0000
@@ -87,17 +87,23 @@
   with beta-redexes
 
   @{ML_response_fake [display, gray]
-"@{term \"(\<lambda>x y. x) 1 2\"}
+"@{term \"(\<lambda>(x::int) (y::int). x)\"} $ @{term \"1::int\"} $ @{term \"2::int\"}
   |> pretty_term @{context}
   |> pwriteln"
   "1"}
 
-  There is a configuration value to switch off the tacit eta-contraction (see
-  \ref{sec:printing}), but none for beta-contraction. So in certain cases you
-  might have to inspect the internal representation of a term, instead of
-  pretty printing it. Because of the alluded puzzlement that might arise from
-  this feature of Isabelle, it is certainly an acrane fact that you should
-  keep in mind about pretty-printing terms.
+  There is a dedicated configuration value for switching off the tacit
+  eta-contraction, namely @{ML_ind eta_contract in Syntax} (see Section
+  \ref{sec:printing}), but none for beta-contractions. However you can avoid
+  the beta-contractions by switching off abbreviation using the configuration
+  value @{ML_ind show_abbrevs in Syntax}. For example
+
+
+  @{ML_response_fake [display, gray]
+  "@{term \"(\<lambda>(x::int) (y::int). x)\"} $ @{term \"1::int\"} $ @{term \"2::int\"}
+  |> pretty_term (Config.put show_abbrevs false @{context})
+  |> pwriteln"
+  "(\<lambda>x y. x) 1 2"}
 
   Isabelle makes a distinction between \emph{free} variables (term-constructor
   @{ML Free} and written on the user level in blue colour) and
diff -r 2862dacb04aa -r d770a7b31aeb progtutorial.pdf
Binary file progtutorial.pdf has changed