On Nov 22, 3:02 pm, Ant <[EMAIL PROTECTED]> wrote: > Hi all, > > I've just been reading with interest this > article:http://caos.di.uminho.pt/~ulisses/blog/2007/11/20/foldr-the-magic-fun... > > It's a useful function that (with a more intuitive name) could prove a > compelling addition to the itertools module. In it's python form, it > would be something like this: > > def reduce2 (fn, init, seq): > return reduce(fn, seq, init) > > def foldr (function, initial): > return partial(reduce2, function, initial) > > It's a bit different from the other itertools functions, in that > rather than producing an iterator, it produces a function which > reduces a iterator to a singe value. > > The advantages I see over reduce are that (a) it provides incentive to > document the code and (b) it promotes reuse. For example: > > value = reduce(lambda x, y: "%s%s%s" % (x, "," if x else "", y), > myList, "") > > vs. > > commaSeparate = foldr(lambda x, y: "%s%s%s" % (x, "," if x else "", > y), "") > commaSeparate(myList) > > Of course the lambda function in this case could be a named function, > helping with both readability and reuse, but I think the latter is > conceptually easier to grasp when reading the code. > > Discuss. > > -- > Ant.
It's basically just one line to implement: foldr = lambda f, i: lambda s: reduce(f, s, i) It's just reduce with currying, I'm not sure it adds that much to what python already offers. -- http://mail.python.org/mailman/listinfo/python-list
