Separating record returned from function in postgres

Question

I've got a function that returns two parameters as an anonymous composite type via output parameters.

I can access the individual columns with a query like this:

# select * from guess_user('Joe','Bloggs');
 confidence | matchid 
------------+---------
   0.142857 |    1121

Now I want to combine the output from this function with some data:

# select firstname,lastname from users limit 5;
 firstname | lastname 
-----------+----------
 Adam      | Smith
 Amy       | Peters
 Annette   | Bloggs
 Annie     | Mills
 Amanda    | Hibbins

I am looking for a query that will output the following:

 firstname | lastname | confidence | matchid 
-----------+----------+------------+---------
 Adam      | Smith    |            | 
 Amy       | Peters   |            | 
 Annette   | Bloggs   |            | 
 Annie     | Mills    |            | 
 Amanda    | Hibbins  |            | 

With the confidence and matchid columns filled out using the results of calling guess_user with the names from that row.

My current closest effort is:

# select firstname, lastname, guess_user(firstname, lastname) from users limit 5;

Which returns:

 firstname | lastname  |  guess_user   
-----------+-----------+---------------
 Angela    | Abbott    | (0.285714,3)
 Amy       | Allan     | (0.285714,4)
 Annette   | Allison   | (0.285714,5)
 Annie     | Ashworth  | (0.285714,6)
 Amanda    | Baird     | (0.285714,7)

Is there a way to split the guess_user output into separate columns?

Answer 1

combining depesz and fazal's answers this seems to work:

select firstname, lastname, (guess_user(firstname, lastname)).*
from users
limit 5