What is the most efficient way to concatenate a string from all parent rows using T-SQL?

I have a table that has a self-referencing foreign key that represents its parent row. To illustrate the problem in its simplest form we'll use this table:

CREATE TABLE Folder(
    id int IDENTITY(1,1) NOT NULL, --PK
    parent_id int NULL,        --FK
    folder_name varchar(255) NOT NULL)

I want to create a scalar-valued function that would return a concatenated string of the folder's name and all its parent folder names all the way to the root folder, which would be designated by a null parent_id value.

My current solution is a procedural approach which I assume is not ideal. Here is what I'm doing:

CREATE FUNCTION dbo.GetEntireLineage
    (@folderId INT)
    RETURNS VARCHAR(MAX)
AS
BEGIN
    DECLARE @lineage VARCHAR(MAX)
    DECLARE @parentFolderId INT

    SELECT @lineage = folder_name, @parentFolderId = parent_id FROM Folder WHERE id = @folderId

WHILE NOT @parentFolderId IS NULL
    BEGIN
        SET @parentFolderId = (SELECT parent_id FROM Folder WHERE parent_id = @parentFolderId)
        SET @lineage = (SELECT @lineage + '-' + (SELECT folder_name FROM Folder WHERE parent_id = @parentFolderId))
    END
RETURN @lineage
END

Is there a more ideal way to do this? I'm an experienced programmer but T-SQL not a familiar world to me and I know these problems generally require a different approach due to the nature of set based data. Any help finding a solution or any other tips and tricks to deal with T-SQL would be much appreciated.