scala - String literal not interpreted as type String -

i'm trying implement simple subclass of iterable[string], , i'm encountering seems bit strange me. code follows:

class itstring[string] extends iterable[string]{     override def iterator: iterator[string] = new iterator[string] {         def hasnext = true         def next = "/"     } } 

my ide complains it's expecting string it's of type string, , when trying compile, further reveals problem requires string literal of type java.lang.string. now, can fix changing "/".asinstanceof[string], i'd know why scala isn't recognising type correctly.

since can following compile:

class itstring extends iterable[string] {   override def iterator: iterator[string] = new iterator[string] {     def hasnext = true     def next = "/"   } } 

i can deduce problem writing:

class itstring[string] extends ... 

what's going on occurrence of string doesn't refer type java.lang.string, instead unknown parameterised type (like t or a). so, when write [string], means some unknown type determined implementing class rather the string type intended.