Add an intermezzo about the id function.

diff --git a/Chapters/Prototype.tex b/Chapters/Prototype.tex
index bad0d0647646f97ac552c97b4b6feb0d68d90ba9..b391d4fcbc6951c2c86af451b805cec8187aae28 100644 (file)
--- a/Chapters/Prototype.tex
+++ b/Chapters/Prototype.tex
@@ -677,6 +677,22 @@
       families and other non-standard Haskell stuff which we do not (plan to)
       support.
 
       families and other non-standard Haskell stuff which we do not (plan to)
       support.
 

+      \placeintermezzo{}{
+        \startframedtext[width=8cm,background=box,frame=no]
+        \startalignment[center]
+          {\tfa The \hs{id} function}
+        \stopalignment
+        \blank[medium]
+          A function that is probably present in every functional language, is
+          the \emph{identity} function. This is the function that takes a
+          single argument and simply returns it unmodified. In Haskell this
+          function is called \hs{id} and can take an argument of any type
+          (\ie, it is polymorphic).
+
+          The \hs{id} function will be used in the examples every now and
+          then.
+        \stopframedtext
+      }

       In Core, every expression is typed. The translation to Core happens
       after the typechecker, so types in Core are always correct as well
       (though you could of course construct invalidly typed expressions
       In Core, every expression is typed. The translation to Core happens
       after the typechecker, so types in Core are always correct as well
       (though you could of course construct invalidly typed expressions