Difficulty performing actions in a finite loop with user input - loops

Question

I'm using Allegro CL Express on a Mac and I'm not sure if the program is having difficulties, or my code is poorly formed. I'm trying to take 4 user input integers and then add them after the last value is entered
Desired outcome:
(stuff)
Enter a number: 4
Enter a number: 3
Enter a number: 2
Enter a number: 1
10
Here's what I currently have:
(defun stuff ()
(loop repeat 4
sum (format t "Enter a number: ")
(parse-integer (read-line))))
EDIT:
After some great help, here is what I have:
CG-USER(18): (defun stuff ()
(loop repeat 4
sum (progn
(format t "Enter a number: ")
(parse-integer (read-line)))))
STUFF
CG-USER(19): (stuff)
Enter a number: 1
It just hangs after I enter an integer and press return.

Answer 1

Using a compiler helps. Look what SBCL says when evaluating your form:
CL-USER> (defun stuff ()
(loop repeat 4
sum
(format t "Enter a number: ")
(parse-integer (read-line))))
; in: DEFUN STUFF
; (LOOP REPEAT 4
; SUM (FORMAT T "Enter a number: ") (PARSE-INTEGER (READ-LINE)))
;
; caught ERROR:
; during macroexpansion of (LOOP REPEAT 4 ...). Use *BREAK-ON-SIGNALS* to
; intercept.
;
; (PARSE-INTEGER
; (READ-LINE)) found where a LOOP keyword or LOOP type keyword expected
; current LOOP context: SUM (FORMAT T "Enter a number: ") (PARSE-INTEGER
; (READ-LINE)).
;
; compilation unit finished
; caught 1 ERROR condition
STUFF
The most important part there is
; (PARSE-INTEGER
; (READ-LINE)) found where a LOOP keyword or LOOP type keyword expected
; current LOOP context: SUM (FORMAT T "Enter a number: ") (PARSE-INTEGER
; (READ-LINE)).
So it's getting (PARSE-INTEGER (READ-LINE)) where a loop keyword or type is expected. Why's that? The documentation for loop should tell us. sum is a numeric accumulation:
numeric-accumulation::= { count | counting | sum |
summing | maximize | maximizing |
minimize | minimizing }
{form | it}
[into simple-var] [type-spec]
So, after sum, there should be a single form. You'd just need to wrap your prompt and the call to read-line in, e.g., a progn to produce a single form:
(defun stuff ()
(loop repeat 4
sum (progn
(format *query-io* "Enter a number: ")
(parse-integer (read-line *query-io*)))))
Note also that I used the stream *query-io* for input and output. You don't have to do that, but it's probably a bit more robust, since:
The value of *query-io*, called query I/O, is a bidirectional stream
to be used when asking questions of the user. The question should be
output to this stream, and the answer read from it.