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I've added a new function to itertools called 'concat'. This function is much like chain, but takes all of the iterables as a single argument. Thus concat(some\_iterables) is logically equivalent to chain(\*some\_iterables); the difference being that chain(\*some\_iterables) results in some\_iterables being fully expanded before the call to chain, while concat(some\_iterables) only iterates on some\_iterables as needed. This makes concat more attractive when some\_iterables is either expensive to expand or "infinite" in length.

Thus, concat(iterable) is like:

 def concat(iterables):  
 for it in iterables:  
 for element in it:  
 yield element

I've attached an updated itertoolsmodule.c file to this email with concat added to it. This was based on the 2.5.1 source.

I ask that this be considered for adoption into standard python.

Thanks in advance!

\-bruce