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Re: Haskell -> Python

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Ian Kelly <ian.g.kelly@gmail.com> wrote:

> On Fri, Nov 2, 2012 at 1:19 PM,  <foster63@gmail.com> wrote:
>> Is there anything anyone could recommend to make it more "Pythonic"
>> or more functional.  It looks clumsy next to the Haskell. 
> 
> def options(heaps):
>     for i, heap in enumerate(heaps):
>         head = heaps[:i]
>         tail = heaps[i+1:]
>         yield from (head + [x] + tail for x in range(heap))
> 
> "yield from" is Python 3.3 syntax.  If you're not using Python 3.3,
> then that line could be replaced by:
> 
>         for x in range(heap):
>             yield head + [x] + tail
> 
> Cheers,
> Ian

An alternative that is closer to foster63's original but still more 
"Pythonic" for some definitions of those words.

def options(heaps):
    if not heaps: return []
    head, *tail = heaps
    for h in range(head):
        yield [h]+tail
    for t in options(tail):
        yield [head]+t

For a more 'functional' version there is also the Python 3.3 variant:

def options(heaps):
    if not heaps: return []
    head, *tail = heaps
    yield from ([h]+tail for h in range(head))
    yield from ([head]+t for t in options(tail))

-- 
Duncan Booth http://kupuguy.blogspot.com

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Haskell -> Python foster63@gmail.com - 2012-11-02 12:19 -0700
  Re: Haskell -> Python Dave Angel <d@davea.name> - 2012-11-02 15:56 -0400
    Re: Haskell -> Python Simon Foster <simon.foster@inbox.com> - 2012-11-02 20:09 +0000
  Re: Haskell -> Python Ian Kelly <ian.g.kelly@gmail.com> - 2012-11-02 15:40 -0600
    Re: Haskell -> Python Duncan Booth <duncan.booth@invalid.invalid> - 2012-11-03 16:29 +0000
  Re: Haskell -> Python Ian Kelly <ian.g.kelly@gmail.com> - 2012-11-02 15:46 -0600
  Re: Haskell -> Python Dave Angel <d@davea.name> - 2012-11-02 18:24 -0400
  Re: Haskell -> Python Ian Kelly <ian.g.kelly@gmail.com> - 2012-11-02 16:27 -0600
  Re: Haskell -> Python Dave Angel <d@davea.name> - 2012-11-02 22:03 -0400
  Re: Haskell -> Python aahz@pythoncraft.com (Aahz) - 2012-11-03 22:16 -0700

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