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[Python-ideas] Python Users Aren't Perfect

Georg Brandl g.brandl at gmx.net
Thu Dec 15 21:51:01 CET 2011 
On 12/15/2011 09:42 PM, Ned Batchelder wrote:
> On 12/15/2011 3:24 PM, Georg Brandl wrote:
>> On 12/13/2011 03:44 AM, Stephen J. Turnbull wrote:
>>> Greg Ewing writes:
>>>   >  Masklinn wrote:
>>>   >
>>>   >  >  FWIW, Haskell does not have a literal singleton (the standard defines
>>>   >  >  "unit" `()` and 2-tuple through 15-tuple)
>>>   >
>>>   >  That's because, due to its static typing, there is no
>>>   >  reason you would ever need to use a 1-tuple rather than
>>>   >  a bare value. We're not that lucky in Python, though.
>>>
>>> I think you have misstated your point?  That's not due to static
>>> typing, that's because you may *always* identify 1-factor products
>>> with the only factor, and Haskell made a deliberate decision to
>>> consistently represent the isomorphism class by the factor rather than
>>> the product.
>> Well, I would say the reason is that the type "tuple of any length" does
>> not exist in Haskell.  So there's no way you will have to pass a 1-tuple
>> to a function that operates on tuples only.
>>
>> But of course, if we all used tuples as tuples only, we wouldn't have to do
>> that either.  It's only because we use tuples as sequences every so often.
> This is another place where Python is inconsistent.  We're told, "lists 
> are for homogenous sequences of varying length, like a C array; tuples 
> are for heterogenous aggregations of known length, like a C struct."   
> Then we define a function foo(*args), and Python gives us a tuple!  :-(

Yep. To be consistent, we'd need an "immutable list" type...
another thing that Haskell has no need for :)

Georg
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