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[Python-Dev] accumulator display semantics

Ian Bicking ianb at colorstudy.com
Thu Oct 16 12:17:35 EDT 2003 
On Thursday, October 16, 2003, at 05:00 AM, Alex Martelli wrote:
> Why not move the for loop, if needed, out of the hard-coded
> infrastructure and just have accumulator display syntax such as:
>     acc[x*x for x in it]
> be exactly equivalent to:
>     a = acc.__accum__(lambda x: x*x, iter(it))
>     return a.result()
> i.e., pass the callable corresponding to the expression, and the
> iterator corresponding to the sequence, to the user-coded
> accumulator.

Seems simpler if you could get an iterator for [x*x for x in it] that 
returned (x*x, x), then call acc.__accum__(that_iter).  I suppose for 
some accumulators you could sometimes avoid calling the expression, but 
that doesn't seem like a big feature.

It seems like it complicates the semantics that you have to turn the 
list comprehension's expression into a function, where (I imagine) it 
doesn't get turned into a real function otherwise, but is executed 
without a new scope.

--
Ian Bicking | ianb at colorstudy.com | http://blog.ianbicking.org
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