Stream implementation's filter function overflows

[Prateem Mandal]

Hi,

I am implementing lazy list using the example in the book FP in  Scala and I found that it fails when I try to search for prime numbers in fibonacci series. The issue seem to be with filter implementation. If I replace the filter implementation using foldRight with pattern matching, then it seems to work fine.

This is how I am checking for primes on fibonacci

Stream fibs = Stream[BigInt](0, 1) append unfold[BigInt, (BigInt, BigInt)]((0, 1))(_ match { case (a, b) => Some((a + b, (b, a + b))) })

println(fibs.filter(_.isProbablePrime(8)).drop(21).headOption)

Here is my implementation (which is identical to Stream implementation in the book and two filter implementation

1) 'filter' with pattern matching which works and

2) 'filter_overflow' which is like the one in the book and overflows)

Any ideals?

Thanks

Prateem

[Prateem Mandal]

Adding the gist

https://gist.github.com/anonymous/73b94c6d7c7d5aa030cb89c5b7c78109

 

Any ideals?

Thanks

Prateem