Add nice summary by Marcin 'Qrczak' Kowalczyk from c.l.py for and

against unifying ints and rats.

pep-0239.txt

@@ -71,6 +71,37 @@ Open Issues
     - Should shift and mask operators be allowed for rational numbers?
       For rational numbers with integer values?
 
+    - Marcin 'Qrczak' Kowalczyk summarized the arguments for and
+      against unifying ints with rationals nicely on c.l.py:
+
+      Arguments for unifying ints with rationals:
+
+      - Since 2 == 2/1 and maybe str(2/1) == '2', it reduces surprises
+        where objects seem equal but behave differently.
+
+      - / can be freely used for integer division when I *know* that
+        there is no remainder (if I am wrong and there is a remainder,
+        there will probably be some exception later).
+
+      Arguments against:
+
+      - When I use the result of / as a sequence index, it's usually
+        an error which should not be hidden by making the program
+        working for some data, since it will break for other data.
+
+      - (this assumes that after unification int and rational would be
+        different types:) Types should rarely depend on values. It's
+        easier to reason when the type of a variable is known: I know
+        how I can use it. I can determine that something is an int and
+        expect that other objects used in this place will be ints too.
+
+      - (this assumes the same type for them:) Int is a good type in
+        itself, not to be mixed with rationals.  The fact that
+        something is an integer should be expressible as a statement
+        about its type. Many operations require ints and don't accept
+        rationals. It's natural to think about them as about different
+        types.
+
 
 References