[Python-Dev] accumulator display syntax

Tim Peters tim_one at email.msn.com
Wed Oct 22 22:30:05 EDT 2003

[Gareth McCaughan]
> <pedant>
> "Aussonderungsaxiom" is the axiom of *separation*[1], which is
> a weakened version of the (disastrous) axiom of *comprehension*.

Ya, sez you <wink>.  Seriously, I don't think the usage is as consistent as
you would have us believe here.  When listcomps were introduced, I suggested
at the time that "list separations" would be a better name for them (for the
reason you gave), but the historical precedent set by SETL, and carried over
into Haskell, means "comprehension" will stick forever in this context.  I
don't think the distinction is consistent across math texts either.

> In terms of Python's listcomps, comprehension would be [x if P(x)]
> and separation [x for x in S if P(x)]. So we should be
> calling them "list separations", really :-).

Yes, we should.  SETL and Haskell also required specifying a base set (or
list) from which elements are chosen, so they also should have called them

>     [1] Hence the name; compare English "sunder".
> For the record, I like "generator expressions" too, or "iterator
> </pedant>

Good!  Guido has decided you love the former, and I agree <wink>.

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