language design - Why are all of the base immutable collections final or sealed in scala? -

language design - Why are all of the base immutable collections final or sealed in scala? -

i wrote trait sorting iterables in scala, , took long create class mix in took write trait. why design decision made disallow users writing things like:

new list[int] superawesometrait[int]?

now if want this, need weird hack like,

class stupidlist extends linearseq { val inner = list() /* reimplement list methods calling inner */ }

and then

new stupidlist[int] superawesometrait[int].

because if write

somelist match { case cons(head, tail) => whatever case nil => somethingelse }

i don't want logic broken new, unexpected subclass.

i suspect you're trying solve problem using subclassing improve solved implicits.

scala language-design