scala - Megre two sorted Array, List vs Array -

this function merges 2 sorted lists. takes 2 lists parameter , returns one.

def merge(xs : list[int], ys : list[int]) : list[int] = {   (xs, ys) match {     case (nil, nil) => nil     case (nil, ys) => ys     case (xs, nil) => xs     case (x :: xs1, y :: ys1) =>       if(x < y) x :: merge(xs1, ys)       else y :: merge(xs, ys1)   } } 

i wanted rewrite function changing parameter type list array, , did not work. however, going list seq worked. tell me not work arrays?

def mergedontwork(xs : array[int], ys : array[int]) : array[int] = {   (xs, ys) match {     case (array.empty,array.empty) => array.empty     case (array.empty, ys) => ys     case (xs, array.empty) => xs     case (x +: xs1, y +: ys1) => if(x < y) x +: merge2(xs1, ys)       else y +: merge2(xs, ys1)   } } 

the error comes part of code : if(x < y) x +: merge2(xs1, ys) : array[any] not conform expected type array[int]

edit

i understood how go list array solutions proposed pedromss , harald. modified function making tail recursive.

    def mergetailrecursion(xs : array[int], ys : array[int]) : array[int] ={         def recurse( acc:array[int],xs:array[int],ys:array[int]):array[int]={              (xs, ys) match {                   case (array(),array()) => acc                  case (array(), ys) => acc++ys                  case (xs, array()) => acc++xs                  case (a@array(x, _*), b@array(y, _*)) =>                      if (x < y) recurse(acc:+x, a.tail, b)                            else     recurse( acc:+y, a, b.tail)             }          }             recurse(array(),xs,ys)      } 

• you can't pattern match on array.empty because method. use array() instead.
• (x +: xs1, y +: ys1) doesn't appear valid match expression. change (x +: xs1, y +: ys1)

compiling version of code:

object arrays extends app {    def merge(xs: array[int], ys: array[int]): array[int] = {     (xs, ys) match {       case (array(), array()) => array.empty       case (array(), ys2)         => ys2       case (xs2, array())         => xs2       case (xs1@array(x, _*), ys1@array(y, _*)) =>         if (x < y) x +: merge(xs1.tail, ys)         else y +: merge(xs, ys1.tail)     }   }    merge(array(1, 2, 3), array(4, 5, 6)).foreach(println)  } 

refer [here|why can't pattern match on stream.empty in scala? explanation pattern matching on methods.

and [here|how pattern match arrays in scala? explanation _*. match number of arguments.

lastlty xs1@, [documentation|https://www.scala-lang.org/files/archive/spec/2.11/08-pattern-matching.html]:

pattern binders

pattern2 ::= varid `@' pattern3

a pattern binder xx@pp consists of pattern variable xx , pattern pp. type of variable xx static type tt of pattern pp. pattern matches value vv matched pattern pp, provided run-time type of vv instance of tt, , binds variable name value.

you with

case (array(x, _*), array(y, _*)) =>             if (x < y) x +: merge(xs.tail, ys)             else y +: merge(xs, ys.tail)