Re: StackOverFlowError When Applying Filter to a Stream

The first time, the filter is part of fibs, the second time it is part 
of another stream accessing fibs. In the first case there are simply not 
enough values left to continue the stream.

On 05.08.2015 20:16, [email protected] wrote:
>
> Hello,
>
>
> Please can some one explain why the following code blows the stack:
>
> |
> |
> |val  fibs:  Stream[BigInt]  =  BigInt(0)  #::  BigInt(1)  #::  fibs.zip(fibs.tail).map{  n=>  n._1+  n._2}.takeWhile(x=>  x<  4000000).filter(x=>  x%  2  ==  0)
>
> scala>  fibs foreach println
> 0
> 1
> java.lang.StackOverflowError|
>
> If I take out the filter and apply it to the stream in another 
> expression as follows, it is fine:
>
> |scala>  val  fibs:  Stream[BigInt]  =  BigInt(0)  #::  BigInt(1)  #::  fibs.zip(fibs.tail).map{  n=>  n._1+  n._2}.takeWhile(x=>  x<  4000000)
> fibs:  Stream[scala.math.BigInt]  =  Stream(0,  ?)
>
> scala>  fibs filter(  x=>  x%  2  ==  0)
> res8:  scala.collection.immutable.Stream[scala.math.BigInt]  =  Stream(0,  ?)
>
> scala>  fibs filter(  x=>  x%  2  ==  0)  foreach println
> 0
> 2
> 8
> 34
> 144
> 610
> 2584
> 10946
> 46368
> 196418
> 832040
> 3524578|
>
> Why does it blow the stack with the first approach but not the second?
>
>
> Thanks
>
> Iftikhar
>
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