"in"consistency?

[Gary Herron]

Nick Dumas wrote:
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> [1,2] in [1,2,3] checks to see if the list [1,2] is an item in [1,2,3].
> Because the list [1,2,3] only contains the integers 1,2,3, the code
> returns a False. Try "[1,2] in [[1,2],[2,3]]"
>   

The inconsistency goes deeper than that.  For instance, the type of a 
value returned by the indexing operation:

   Indexing a string returns a string (of length 1 of course),
   while indexing a list does not (necessarily) return a list.

Conclusion:  They are different types supporting different operations.  
Given all the obvious differences (mutability, sorting and other 
methods, types of individual elements), I'd say there are more 
differences than similarities, even though, as sequences,  they both 
support a small subset of similar operations.

Gary Herron




> David C. Ullrich wrote:
>   
>> Luckily I tried it before saying no, that's
>> not how "in" works:
>>
>>     
>>>>> 'ab' in 'abc'
>>>>>           
>> True
>>     
>>>>> [1,2] in [1,2,3]
>>>>>           
>> False
>>
>> Is there a reason for the inconsistency? I would
>> have thought "in" would check for elements of a
>> sequence, regardless of what sort of sequence it was...
>>
>>     
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