Tokenize Replace file type


Sorry bit of a noob here
I just want to replace the extension of the original file name with abc lol :(.
I keep getting error, Illegal operation “+” on data of type string[].
I see how this makes sense but idk how to fix this.

string $s = (file -q -sn);
string $Directory[];
tokenize $s “.” $Directory;

string $DirPlusFtype[] = $Directory + "abc";


Anything would be greatly appreciated