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# lambda-hacker/zip.scala Secret

Last active Aug 29, 2015
zip exercises [Scala]
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 // zip3 Lists object ZipUtils { def zip3[A, B, C] (xs: List[A], ys: List[B], zs: List[C]) : List[(A, B, C)] = { def zip3_aux(xs: List[A], ys: List[B], zs: List[C], acc: List[(A, B, C)]) : List[(A, B, C)] = (xs, ys, zs) match { case (Nil, _, _) | (_, Nil, _) | (_, _, Nil) => acc case (xh::xt, yh::yt, zh::zt) => zip3_aux (xt, yt, zt, (xh, yh, zh) :: acc ) } zip3_aux(xs, ys, zs, Nil).reverse } def zipWith [A, B] (f: (A, B) => Any) (xs: List[A], ys: List[B]) : List[Any] = { xs zip ys map { case (x, y) => f(x, y) } } // zip3 Vectors def zip3[A, B, C] (xs: Vector[A], ys: Vector[B], zs: Vector[C]) : Vector[(A, B, C)] = { val l = xs.length min ys.length min zs.length def zipaux (v: Int, acc: Vector[(A, B, C)]) : Vector[(A, B, C)] = if (v == 0) acc else zipaux(v - 1, acc :+ ( xs(l - v), ys(l - v), zs(l - v) )) zipaux (l, Vector.empty) } def zip3Vec[A, B, C] (xs: Vector[A], ys: Vector[B], zs: Vector[C]) : Vector[(A, B, C)] = { val l = xs.length min ys.length min zs.length (0 to l-1).toVector.map(i => (xs(i), ys(i), zs(i))) } }

### tabrez commented Feb 10, 2015

 https://gist.github.com/tabrez/b86bb73baf2dde24b7c5 Try to write zip3 using higher-order functions without worrying about efficiency. Add some example calls to these methods.