Usage of the supine form without "har"
While reading a book, I have on several occasions encountered sentences like "Tack för att du kommit". Obviously, the missing "har" kind of surprised me and so I googled "Tack för att du har kommit" and it seems it's used as well. Is the former just a colloquialism or are both of them equally correct? In case that they are equal, it is not always possible to omit "har", as in "Jag köpt en ny bil", am I right? Cheers.
You can omit both har and hade in a subordinate clause, as in:
Det här är bilen som du [har] köpt "This is the car that you have bought"
Jag vet att hon [har] tagit den! "I know that she has taken it"
Vet du om han [har] gjort det? "Do you know if he has done that?"
Om du [hade] sagt det, skulle vi inte vara här nu! "If you had said so, we wouldn't be here now!"
This is a typical feature of written Swedish. It does occur in the spoken language as well, but less frequently so.