An argument for DSL's

loop expansion.lisp

;; The following two functions are equivalent:

(loop repeat 10 for x = 0 then y and y = 1 then (+ x y) collect y) ; ===> (1 1 2 3 5 8 13 21 34 55)

(BLOCK NIL
  (LET ((#:LOOP-REPEAT-876 (CEILING 10)) (X NIL) (Y NIL))
    (DECLARE (TYPE INTEGER #:LOOP-REPEAT-876))
    (SB-LOOP::WITH-LOOP-LIST-COLLECTION-HEAD (#:LOOP-LIST-HEAD-877
                                              #:LOOP-LIST-TAIL-878)
      (SB-LOOP::LOOP-BODY NIL
                          ((IF (<= #:LOOP-REPEAT-876 0)
                               (GO SB-LOOP::END-LOOP)
                               (DECF #:LOOP-REPEAT-876))
                           NIL
                           (SB-LOOP::LOOP-REALLY-DESETQ X
                                                        (PROG1 0
                                                          (SB-LOOP::LOOP-REALLY-DESETQ
                                                           Y 1)))
                           NIL NIL)
                          ((SB-LOOP::LOOP-COLLECT-RPLACD
                            (#:LOOP-LIST-HEAD-877 #:LOOP-LIST-TAIL-878)
                            (LIST Y)))
                          ((IF (<= #:LOOP-REPEAT-876 0)
                               (GO SB-LOOP::END-LOOP)
                               (DECF #:LOOP-REPEAT-876))
                           NIL
                           (SB-LOOP::LOOP-REALLY-DESETQ X
                                                        (PROG1 Y
                                                          (SB-LOOP::LOOP-REALLY-DESETQ
                                                           Y (+ X Y))))
                           NIL NIL)
                          ((RETURN-FROM NIL
                             (SB-LOOP::LOOP-COLLECT-ANSWER
                              #:LOOP-LIST-HEAD-877)))))))  ; ===> (1 1 2 3 5 8 13 21 34 55)