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Re: Fear and suspicion of lambdas, was Re: Meta decorator with parameters, defined in explicit functions

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Lawrence D’Oliveiro wrote:

> On Thursday, June 30, 2016 at 7:26:01 PM UTC+12, Peter Otten wrote:
>> foo = lambda <args>: <expr>
>> 
>> there is syntactic sugar in Python that allows you to write it as
>> 
>> def foo(<args>):
>>     return <expr>
>> 
>> with the nice side effects that it improves the readability of tracebacks
>> and allows you to provide a docstring.
> 
> True, but then again the original had three lambdas, so one line would
> have to become at least 3×2 = 6 lines, more if you want docstrings.
> 
>> def reduce(items, func=lambda x, y: x + y): ...
> 
> There was a reason why “reduce” was removed from being a builtin function
> in Python 2.x, to being banished to functools in Python 3.

You do understand what an example is?

 
>> the alternative
>> 
>> def reduce(items, func=add): ...
>> 
>> looks more readable in my eyes even though somewhere ...
> 
> Just use “sum” in this case.

Nah, the implementation is of course

def reduce(items, func=lambda x, y: x + y):
    """
    >>> list(reduce([1,2,3]))
    [1, 3, 6]

    >>> list(reduce([42]))
    [42]

    >>> reduce([])
    Traceback (most recent call last):
        ...
    TypeError: reduce() with empty sequence
    """
    items = iter(items)
    try:
        first = next(items)
    except StopIteration:
        raise TypeError("reduce() with empty sequence")

    def _reduce(accu=first):
        for item in items:
            yield accu
            accu = func(accu, item)
        yield accu

    return _reduce()

Yes, I'm kidding...

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Meta decorator with parameters, defined in explicit functions Ben Finney <ben+python@benfinney.id.au> - 2016-06-28 15:02 +1000
  Re: Meta decorator with parameters, defined in explicit functions Paul Rubin <no.email@nospam.invalid> - 2016-06-27 23:08 -0700
  Re: Meta decorator with parameters, defined in explicit functions Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2016-06-28 18:39 +1000
  Re: Meta decorator with parameters, defined in explicit functions Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-06-29 19:43 -0700
    Re: Meta decorator with parameters, defined in explicit functions Steven D'Aprano <steve@pearwood.info> - 2016-06-30 13:49 +1000
    Fear and suspicion of lambdas, was Re: Meta decorator with parameters, defined in explicit functions Peter Otten <__peter__@web.de> - 2016-06-30 09:25 +0200
      Re: Fear and suspicion of lambdas, was Re: Meta decorator with parameters, defined in explicit functions Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-06-30 00:43 -0700
        Re: Fear and suspicion of lambdas, was Re: Meta decorator with parameters, defined in explicit functions Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2016-06-30 18:00 +1000
        Re: Fear and suspicion of lambdas, was Re: Meta decorator with parameters, defined in explicit functions Peter Otten <__peter__@web.de> - 2016-06-30 10:41 +0200
    Re: Fear and suspicion of lambdas, was Re: Meta decorator with parameters, defined in explicit functions dieter <dieter@handshake.de> - 2016-07-01 09:04 +0200
      Re: Fear and suspicion of lambdas, was Re: Meta decorator with parameters, defined in explicit functions Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-07-01 21:25 +0100
        Re: Fear and suspicion of lambdas, was Re: Meta decorator with parameters, defined in explicit functions Ben Finney <ben+python@benfinney.id.au> - 2016-07-02 11:52 +1000
        Re: Fear and suspicion of lambdas, was Re: Meta decorator with parameters, defined in explicit functions dieter <dieter@handshake.de> - 2016-07-02 08:57 +0200
        Re: Fear and suspicion of lambdas, was Re: Meta decorator with parameters, defined in explicit functions Ben Finney <ben+python@benfinney.id.au> - 2016-07-02 18:00 +1000
  Re: Meta decorator with parameters, defined in explicit functions Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-06-29 19:50 -0700
  Re: Meta decorator with parameters, defined in explicit functions Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-07-01 15:08 -0700
    Re: Meta decorator with parameters, defined in explicit functions Ian Kelly <ian.g.kelly@gmail.com> - 2016-07-01 23:09 -0600
      Re: Meta decorator with parameters, defined in explicit functions Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-07-01 23:40 -0700
        Re: Meta decorator with parameters, defined in explicit functions Ian Kelly <ian.g.kelly@gmail.com> - 2016-07-02 22:48 -0600
          Re: Meta decorator with parameters, defined in explicit functions Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-07-02 22:37 -0700
            Re: Meta decorator with parameters, defined in explicit functions Ian Kelly <ian.g.kelly@gmail.com> - 2016-07-03 05:52 -0600
              Re: Meta decorator with parameters, defined in explicit functions Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-07-03 14:17 -0700
                Re: Meta decorator with parameters, defined in explicit functions Ian Kelly <ian.g.kelly@gmail.com> - 2016-07-03 16:38 -0600
                Re: Meta decorator with parameters, defined in explicit functions Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-07-03 16:25 -0700
                Re: Meta decorator with parameters, defined in explicit functions Chris Angelico <rosuav@gmail.com> - 2016-07-04 09:39 +1000
                Re: Meta decorator with parameters, defined in explicit functions Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-07-03 16:59 -0700
                Re: Meta decorator with parameters, defined in explicit functions Chris Angelico <rosuav@gmail.com> - 2016-07-04 10:06 +1000
                Re: Meta decorator with parameters, defined in explicit functions Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-07-03 17:23 -0700
                Re: Meta decorator with parameters, defined in explicit functions Ian Kelly <ian.g.kelly@gmail.com> - 2016-07-03 18:01 -0600
                Re: Meta decorator with parameters, defined in explicit functions Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-07-03 17:06 -0700
                Re: Meta decorator with parameters, defined in explicit functions Ian Kelly <ian.g.kelly@gmail.com> - 2016-07-03 18:20 -0600
    Re: Meta decorator with parameters, defined in explicit functions Ben Finney <ben+python@benfinney.id.au> - 2016-07-02 15:32 +1000
    Re: Meta decorator with parameters, defined in explicit functions Ian Kelly <ian.g.kelly@gmail.com> - 2016-07-01 23:53 -0600

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