Lazy lists

[spir]

On 02/23/2011 01:57 PM, Andrei Alexandrescu wrote:
> On 2/23/11 5:10 AM, Jacob Carlborg wrote:
>> On 2011-02-23 03:28, bearophile wrote:
>>> This is a Scala implementation of a function that prints the carpet:
>>>
>>>
>>> def nextCarpet(carpet: List[String]): List[String] = (
>>> carpet.map(x => x + x + x) :::
>>> carpet.map(x => x + x.replace('#', ' ') + x) :::
>>> carpet.map(x => x + x + x))
>>>
>>> def sierpinskiCarpets(n: Int) =
>>> (Iterator.iterate(List("#"))(nextCarpet) drop n next) foreach println
>>
>> Again Scala shines with its beautiful lambdas compared to Ds ugly string
>> version.
>
> But then
>
> Iterator.iterate(List("#"))(nextCarpet) drop n next) foreach println
>
> a sort of a stuttering Yoda evokes.

lol :-)

It just requires being used to stack-based-like lingo; meaning each step is 
written in chrono-logical order, from left to right. Well, actually, the 
'List("#")' part looks like a useless hack, and 'Iterator.iterate' is somewhat 
verbose. I'd prefere:
     (sequence(["#"])(nextCarpet) drop n next) foreach println

Denis
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