[Python-ideas] Statements vs Expressions... why?

[Cliff Wells]

On Tue, 2008-09-16 at 13:06 +1200, Greg Ewing wrote:
> Cliff Wells wrote:
> 
> > s = 'abc'
> > x = for c in s: YIELD c     # x = 'a', 'b', 'c'
> 
> You mean that the value of (for c in s: YIELD c) is
> a tuple? Or that it's an iterator that produces that
> series of values?
> 
> > I = [ 'spam', 'eggs' ]
> > 
> > for J in I:                 # J = 'spam' then 'eggs'
> >     YIELD (                 # evaluate to an iterable
> >         for j in J: YIELD j # j is 's' then 'p' then ...
> >     )
>  >
>  > so we get '-'.join( 's','p','a','m','e','g','g','s' )
> 
> I'm still not getting a clear idea of what semantics
> you intend for a for-loop-with-YIELD. Neither of the
> interpretations I suggested above (sequence or iterator)
> seems to produce this result.

Actually, I think I see the issue.  join() is getting a list of
iterators (using list notation for simplicity): 

'-'.join ( [ [ 's','p','a','m'], ['e','g','g','s'] ] )

(I promise you I'm not being intentionally obtuse).

Is this the conclusion you were coming to or something else?

Cliff