Inheriting constructor from parent class in scala -

i'm trying understand syntax inheriting 1 class , seems must announce constructor parameters of parent when create child?

why code not compile?

  class animal(name:string)   class dog extends animal //here compiler error occurs 

but does

  class animal(name:string)   class dog(name:string ) extends animal(name) 

is reason must explicitly extends animal(name) , not extends animal , constructor implied?

the scala language specification doesn't (as far can see) discuss reasons, providing implied constructor special case, , arguably less clear.

note can things like:

class animal(name:string) class dog extends animal("dog") 

and

class animal(name:string) class dog(n1: string, n2: string) extends animal(n1 + n2) 

so current behaviour accommodates variety of patterns in uniform , explicit way.