[Python-Dev] PEP 3142: Add a "while" clause to generator expressions

Terry Reedy tjreedy at udel.edu
Wed Jan 21 21:42:05 CET 2009

Steven D'Aprano wrote:
> On Wed, 21 Jan 2009 03:10:24 pm Terry Reedy wrote:
>> Steven D'Aprano wrote:

>>> The three clauses are neither in the same order, nor are they in
>>> reverse order.
>> They are in the same order but rotated, with the last brought around
>> to the front to emphasize it.  Did you really not notice that either?
> There are only three items, of course I noticed that there is *some* 
> rearrangement of the first that leads to the second. Out of the six 
> possible permutations of three items, they can all be described in 
> terms of some sort of reflection, rotation or swap.

Irrelevant.  *Every* comprehension, no matter how many clauses, rotates 
the expression from last to first and keeps the clauses in the same 
order with the same meaning.  Simple rule.

>> Ironically, in a thread cross-posted on c.l.p and elsewhere, someone
>> just labeled Python's comprehension syntax as "ad hoc syntax soup".
> Is that Xah Lee? It sounds like the sort of thing he'd say.

It was the thread he started, but not him.  He contributed other idiocies.

Terry Jan Reedy

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