Clarify the new syntax and note a backwards incompatibility.

pep-0308.txt

@@ -27,6 +27,39 @@ Adding a conditional expression
     sampling of real-world use cases, across a variety of applications,
     written by a number of programmers with diverse backgrounds). [3]
 
+    The following change will be made to the grammar.  (The or_test
+    symbols is new, the others are modified.)
+
+        test: or_test ['if' or_test 'else' test] | lambdef
+        or_test: and_test ('or' and_test)*
+        ...
+        testlist_safe: or_test [(',' or_test)+ [',']]
+        ...
+        gen_for: 'for' exprlist 'in' or_test [gen_iter]
+
+    The new syntax introduces a minor syntactical backwards
+    incompatibility.  In previous Python versions, the following is
+    legal:
+
+        [f for f in lambda x: x, lambda x: x**2 if f(1) == 1]
+
+    (I.e. a list comprehension where the sequence following 'in' is an
+    unparenthesized series of lambdas -- or just one lambda, even.)
+
+    In Python 2.5, the series of lambdas will have to be
+    parenthesized:
+
+        [f for f in (lambda x: x, lambda x: x**2) if f(1) == 1]
+
+    This is because lambda binds less tight than the if-else
+    expression, but in this context, the lambda could already be
+    followed by an 'if' keyword that binds less tightly still (for
+    details, consider the grammar changes shown above).
+
+    Given that this is a rather odd corner of the syntax the BDFL does
+    not believe this backwards incompatibility requires us to use a
+    future statement to enable the new syntax.
+
 
 References