CustomString and string constraints

[SrMordred]

Is possible to make a Custom Struct String work for D string 
constraints?

eg:

struct MyString
{
     char[] arr;
     alias arr this;
}

void getString( char[] str ){}

MyString().split(";"); //oops, type mismatch

getString( MyString() ); //fine, implicit conversion

isSomeString!(char[]).writeln; //true
isSomeString!(MyString).writeln; //false