0.8.8.30:

[sbcl.git] / src / code / loop.lisp

diff --git a/src/code/loop.lisp b/src/code/loop.lisp
index 3ffe823..acabbf6 100644 (file)
--- a/src/code/loop.lisp
+++ b/src/code/loop.lisp
@@ -93,67 +93,6 @@
 ;;;; LOOP-PREFER-POP (not true on CMU CL) and which has since been
 ;;;; removed. Thus, STEP-FUNCTION stuff could probably be removed too.
 \f
 ;;;; LOOP-PREFER-POP (not true on CMU CL) and which has since been
 ;;;; removed. Thus, STEP-FUNCTION stuff could probably be removed too.
 \f

-;;;; miscellaneous environment things
-
-(eval-when (:compile-toplevel :load-toplevel :execute)
-  (defvar *loop-real-data-type* 'real))
-
-(eval-when (:compile-toplevel :load-toplevel :execute)
-  (defvar *loop-gentemp* nil)
-  (defun loop-gentemp (&optional (pref 'loopvar-))
-    (if *loop-gentemp*
-      (gentemp (string pref))
-      (gensym))))
-
-;;; @@@@ The following form takes a list of variables and a form which
-;;; presumably references those variables, and wraps it somehow so that the
-;;; compiler does not consider those variables have been referenced. The intent
-;;; of this is that iteration variables can be flagged as unused by the
-;;; compiler, e.g. I in (loop for i from 1 to 10 do (print t)), since we will
-;;; tell it when a usage of it is "invisible" or "not to be considered".
-;;;
-;;; We implicitly assume that a setq does not count as a reference. That is,
-;;; the kind of form generated for the above loop construct to step I,
-;;; simplified, is
-;;;   `(SETQ I ,(HIDE-VARIABLE-REFERENCES '(I) '(1+ I))).
-;;;
-;;; FIXME: This is a no-op except for Genera, now obsolete, so it
-;;; can be removed.
-(defun hide-variable-references (variable-list form)
-  (declare (ignore variable-list))
-  form)
-
-;;; @@@@ The following function takes a flag, a variable, and a form which
-;;; presumably references that variable, and wraps it somehow so that the
-;;; compiler does not consider that variable to have been referenced. The
-;;; intent of this is that iteration variables can be flagged as unused by the
-;;; compiler, e.g. I in (loop for i from 1 to 10 do (print t)), since we will
-;;; tell it when a usage of it is "invisible" or "not to be considered".
-;;;
-;;; We implicitly assume that a setq does not count as a reference. That is,
-;;; the kind of form generated for the above loop construct to step I,
-;;; simplified, is
-;;;   `(SETQ I ,(HIDE-VARIABLE-REFERENCES T 'I '(1+ I))).
-;;;
-;;; Certain cases require that the "invisibility" of the reference be
-;;; conditional upon something. This occurs in cases of "named" variables (the
-;;; USING clause). For instance, we want IDX in (LOOP FOR E BEING THE
-;;; VECTOR-ELEMENTS OF V USING (INDEX IDX) ...) to be "invisible" when it is
-;;; stepped, so that the user gets informed if IDX is not referenced. However,
-;;; if no USING clause is present, we definitely do not want to be informed
-;;; that some gensym or other is not used.
-;;;
-;;; It is easier for the caller to do this conditionally by passing a flag
-;;; (which happens to be the second value of NAMED-VARIABLE, q.v.) to this
-;;; function than for all callers to contain the conditional invisibility
-;;; construction.
-;;;
-;;; FIXME: This is a no-op except for Genera, now obsolete, so it
-;;; can be removed.
-(defun hide-variable-reference (really-hide variable form)
-  (declare (ignore really-hide variable))
-  form)
-\f

 ;;;; list collection macrology
 
 (sb!int:defmacro-mundanely with-loop-list-collection-head
 ;;;; list collection macrology
 
 (sb!int:defmacro-mundanely with-loop-list-collection-head

@@ -252,9 +191,9 @@ constructed.
     (make-loop-minimax-internal
       :answer-variable answer-variable
       :type type
     (make-loop-minimax-internal
       :answer-variable answer-variable
       :type type

-      :temp-variable (loop-gentemp 'loop-maxmin-temp-)
+      :temp-variable (gensym "LOOP-MAXMIN-TEMP-")

       :flag-variable (and (not infinity-data)
       :flag-variable (and (not infinity-data)

-                         (loop-gentemp 'loop-maxmin-flag-))
+                         (gensym "LOOP-MAXMIN-FLAG-"))

       :operations nil
       :infinity-data infinity-data)))
 
       :operations nil
       :infinity-data infinity-data)))
 

@@ -263,7 +202,7 @@ constructed.
   (when (and (cdr (loop-minimax-operations minimax))
             (not (loop-minimax-flag-variable minimax)))
     (setf (loop-minimax-flag-variable minimax)
   (when (and (cdr (loop-minimax-operations minimax))
             (not (loop-minimax-flag-variable minimax)))
     (setf (loop-minimax-flag-variable minimax)

-         (loop-gentemp 'loop-maxmin-flag-)))
+         (gensym "LOOP-MAXMIN-FLAG-")))

   operation)
 
 (sb!int:defmacro-mundanely with-minimax-value (lm &body body)
   operation)
 
 (sb!int:defmacro-mundanely with-minimax-value (lm &body body)

@@ -289,13 +228,10 @@ constructed.
   (let* ((answer-var (loop-minimax-answer-variable lm))
         (temp-var (loop-minimax-temp-variable lm))
         (flag-var (loop-minimax-flag-variable lm))
   (let* ((answer-var (loop-minimax-answer-variable lm))
         (temp-var (loop-minimax-temp-variable lm))
         (flag-var (loop-minimax-flag-variable lm))

-        (test
-          (hide-variable-reference
-            t (loop-minimax-answer-variable lm)
-            `(,(ecase operation
-                 (min '<)
-                 (max '>))
-              ,temp-var ,answer-var))))
+        (test `(,(ecase operation
+                   (min '<)
+                   (max '>))
+                ,temp-var ,answer-var)))

     `(progn
        (setq ,temp-var ,form)
        (when ,(if flag-var `(or (not ,flag-var) ,test) test)
     `(progn
        (setq ,temp-var ,form)
        (when ,(if flag-var `(or (not ,flag-var) ,test) test)

@@ -390,13 +326,7 @@ code to be loaded.
                            (setf (gethash (car x) ht) (cadr x))))
                      ht))))
 \f
                            (setf (gethash (car x) ht) (cadr x))))
                      ht))))
 \f

-;;;; SETQ hackery
-
-(defvar *loop-destructuring-hooks*
-       nil
-  #!+sb-doc
-  "If not NIL, this must be a list of two things:
-a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.")
+;;;; SETQ hackery, including destructuring ("DESETQ")

 
 (defun loop-make-psetq (frobs)
   (and frobs
 
 (defun loop-make-psetq (frobs)
   (and frobs

@@ -409,19 +339,16 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
 (defun loop-make-desetq (var-val-pairs)
   (if (null var-val-pairs)
       nil
 (defun loop-make-desetq (var-val-pairs)
   (if (null var-val-pairs)
       nil

-      (cons (if *loop-destructuring-hooks*
-               (cadr *loop-destructuring-hooks*)
-               'loop-really-desetq)
-           var-val-pairs)))
+      (cons 'loop-really-desetq var-val-pairs)))

 
 (defvar *loop-desetq-temporary*
        (make-symbol "LOOP-DESETQ-TEMP"))
 
 (sb!int:defmacro-mundanely loop-really-desetq (&environment env
 
 (defvar *loop-desetq-temporary*
        (make-symbol "LOOP-DESETQ-TEMP"))
 
 (sb!int:defmacro-mundanely loop-really-desetq (&environment env

-                                                 &rest var-val-pairs)
+                                              &rest var-val-pairs)

   (labels ((find-non-null (var)
   (labels ((find-non-null (var)

-            ;; see whether there's any non-null thing here
-            ;; recurse if the list element is itself a list
+            ;; See whether there's any non-null thing here. Recurse
+            ;; if the list element is itself a list.

             (do ((tail var)) ((not (consp tail)) tail)
               (when (find-non-null (pop tail)) (return t))))
           (loop-desetq-internal (var val &optional temp)
             (do ((tail var)) ((not (consp tail)) tail)
               (when (find-non-null (pop tail)) (return t))))
           (loop-desetq-internal (var val &optional temp)

@@ -429,17 +356,17 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
             (typecase var
               (null
                 (when (consp val)
             (typecase var
               (null
                 (when (consp val)

-                  ;; don't lose possible side-effects
+                  ;; Don't lose possible side effects.

                   (if (eq (car val) 'prog1)
                   (if (eq (car val) 'prog1)

-                      ;; these can come from psetq or desetq below.
-                      ;; throw away the value, keep the side-effects.
-                      ;;Special case is for handling an expanded POP.
-                      (mapcan #'(lambda (x)
-                                  (and (consp x)
-                                       (or (not (eq (car x) 'car))
-                                           (not (symbolp (cadr x)))
-                                           (not (symbolp (setq x (sb!xc:macroexpand x env)))))
-                                       (cons x nil)))
+                      ;; These can come from PSETQ or DESETQ below.
+                      ;; Throw away the value, keep the side effects.
+                      ;; Special case is for handling an expanded POP.
+                      (mapcan (lambda (x)
+                                (and (consp x)
+                                     (or (not (eq (car x) 'car))
+                                         (not (symbolp (cadr x)))
+                                         (not (symbolp (setq x (sb!xc:macroexpand x env)))))
+                                     (cons x nil)))

                               (cdr val))
                       `(,val))))
               (cons
                               (cdr val))
                       `(,val))))
               (cons

@@ -463,7 +390,7 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
                                 ,@body)
                               `((let ((,temp ,val))
                                   ,@body))))
                                 ,@body)
                               `((let ((,temp ,val))
                                   ,@body))))

-                        ;; no cdring to do
+                        ;; no CDRing to do

                         (loop-desetq-internal car `(car ,val) temp)))))
               (otherwise
                 (unless (eq var val)
                         (loop-desetq-internal car `(car ,val) temp)))))
               (otherwise
                 (unless (eq var val)

@@ -496,36 +423,36 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
 (defvar *loop-macro-environment*)
 
 ;;; This holds variable names specified with the USING clause.
 (defvar *loop-macro-environment*)
 
 ;;; This holds variable names specified with the USING clause.

-;;; See LOOP-NAMED-VARIABLE.
-(defvar *loop-named-variables*)
+;;; See LOOP-NAMED-VAR.
+(defvar *loop-named-vars*)

 
 ;;; LETlist-like list being accumulated for one group of parallel bindings.
 
 ;;; LETlist-like list being accumulated for one group of parallel bindings.

-(defvar *loop-variables*)
+(defvar *loop-vars*)

 
 

-;;; list of declarations being accumulated in parallel with *LOOP-VARIABLES*
+;;; list of declarations being accumulated in parallel with *LOOP-VARS*

 (defvar *loop-declarations*)
 
 ;;; This is used by LOOP for destructuring binding, if it is doing
 (defvar *loop-declarations*)
 
 ;;; This is used by LOOP for destructuring binding, if it is doing

-;;; that itself. See LOOP-MAKE-VARIABLE.
+;;; that itself. See LOOP-MAKE-VAR.

 (defvar *loop-desetq-crocks*)
 
 ;;; list of wrapping forms, innermost first, which go immediately
 ;;; inside the current set of parallel bindings being accumulated in
 (defvar *loop-desetq-crocks*)
 
 ;;; list of wrapping forms, innermost first, which go immediately
 ;;; inside the current set of parallel bindings being accumulated in

-;;; *LOOP-VARIABLES*. The wrappers are appended onto a body. E.g.,
+;;; *LOOP-VARS*. The wrappers are appended onto a body. E.g.,

 ;;; this list could conceivably have as its value
 ;;;   ((WITH-OPEN-FILE (G0001 G0002 ...))),
 ;;; this list could conceivably have as its value
 ;;;   ((WITH-OPEN-FILE (G0001 G0002 ...))),

-;;; with G0002 being one of the bindings in *LOOP-VARIABLES* (This is
+;;; with G0002 being one of the bindings in *LOOP-VARS* (This is

 ;;; why the wrappers go inside of the variable bindings).
 (defvar *loop-wrappers*)
 
 ;;; why the wrappers go inside of the variable bindings).
 (defvar *loop-wrappers*)
 

-;;; This accumulates lists of previous values of *LOOP-VARIABLES* and
+;;; This accumulates lists of previous values of *LOOP-VARS* and

 ;;; the other lists above, for each new nesting of bindings. See
 ;;; LOOP-BIND-BLOCK.
 (defvar *loop-bind-stack*)
 
 ;;; This is simply a list of LOOP iteration variables, used for
 ;;; checking for duplications.
 ;;; the other lists above, for each new nesting of bindings. See
 ;;; LOOP-BIND-BLOCK.
 (defvar *loop-bind-stack*)
 
 ;;; This is simply a list of LOOP iteration variables, used for
 ;;; checking for duplications.

-(defvar *loop-iteration-variables*)
+(defvar *loop-iteration-vars*)

 
 ;;; list of prologue forms of the loop, accumulated in reverse order
 (defvar *loop-prologue*)
 
 ;;; list of prologue forms of the loop, accumulated in reverse order
 (defvar *loop-prologue*)

@@ -563,14 +490,14 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
 ;;; If not NIL, this is a temporary bound around the loop for holding
 ;;; the temporary value for "it" in things like "when (f) collect it".
 ;;; It may be used as a supertemporary by some other things.
 ;;; If not NIL, this is a temporary bound around the loop for holding
 ;;; the temporary value for "it" in things like "when (f) collect it".
 ;;; It may be used as a supertemporary by some other things.

-(defvar *loop-when-it-variable*)
+(defvar *loop-when-it-var*)

 
 ;;; Sometimes we decide we need to fold together parts of the loop,
 ;;; but some part of the generated iteration code is different for the
 ;;; first and remaining iterations. This variable will be the
 ;;; temporary which is the flag used in the loop to tell whether we
 ;;; are in the first or remaining iterations.
 
 ;;; Sometimes we decide we need to fold together parts of the loop,
 ;;; but some part of the generated iteration code is different for the
 ;;; first and remaining iterations. This variable will be the
 ;;; temporary which is the flag used in the loop to tell whether we
 ;;; are in the first or remaining iterations.

-(defvar *loop-never-stepped-variable*)
+(defvar *loop-never-stepped-var*)

 
 ;;; list of all the value-accumulation descriptor structures in the
 ;;; loop. See LOOP-GET-COLLECTION-INFO.
 
 ;;; list of all the value-accumulation descriptor structures in the
 ;;; loop. See LOOP-GET-COLLECTION-INFO.

@@ -584,7 +511,8 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
       (setq constant-value (eval new-form)))
     (when (and constantp expected-type)
       (unless (sb!xc:typep constant-value expected-type)
       (setq constant-value (eval new-form)))
     (when (and constantp expected-type)
       (unless (sb!xc:typep constant-value expected-type)

-       (loop-warn "The form ~S evaluated to ~S, which was not of the anticipated type ~S."
+       (loop-warn "~@<The form ~S evaluated to ~S, which was not of ~
+                    the anticipated type ~S.~:@>"

                   form constant-value expected-type)
        (setq constantp nil constant-value nil)))
     (values new-form constantp constant-value)))
                   form constant-value expected-type)
        (setq constantp nil constant-value nil)))
     (values new-form constantp constant-value)))

@@ -597,7 +525,7 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
 (defvar *loop-duplicate-code*
        nil)
 
 (defvar *loop-duplicate-code*
        nil)
 

-(defvar *loop-iteration-flag-variable*
+(defvar *loop-iteration-flag-var*

        (make-symbol "LOOP-NOT-FIRST-TIME"))
 
 (defun loop-code-duplication-threshold (env)
        (make-symbol "LOOP-NOT-FIRST-TIME"))
 
 (defun loop-code-duplication-threshold (env)

@@ -607,6 +535,11 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
        ;; CLTL2, removed from ANSI standard) we could set these
        ;; values flexibly. Without DECLARATION-INFORMATION, we have
        ;; to set them to constants.
        ;; CLTL2, removed from ANSI standard) we could set these
        ;; values flexibly. Without DECLARATION-INFORMATION, we have
        ;; to set them to constants.

+       ;;
+       ;; except FIXME: we've lost all pretence of portability,
+       ;; considering this instead an internal implementation, so
+       ;; we're free to couple to our own representation of the
+       ;; environment.

        (speed 1)
        (space 1))
     (+ 40 (* (- speed space) 10))))
        (speed 1)
        (space 1))
     (+ 40 (* (- speed space) 10))))

@@ -645,26 +578,27 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
     (when (or *loop-duplicate-code* (not rbefore))
       (return-from loop-body (makebody)))
     ;; This outer loop iterates once for each not-first-time flag test
     (when (or *loop-duplicate-code* (not rbefore))
       (return-from loop-body (makebody)))
     ;; This outer loop iterates once for each not-first-time flag test

-    ;; generated plus once more for the forms that don't need a flag test
+    ;; generated plus once more for the forms that don't need a flag test.

     (do ((threshold (loop-code-duplication-threshold env))) (nil)
       (declare (fixnum threshold))
     (do ((threshold (loop-code-duplication-threshold env))) (nil)
       (declare (fixnum threshold))

-      ;; Go backwards from the ends of before-loop and after-loop merging all
-      ;; the equivalent forms into the body.
+      ;; Go backwards from the ends of before-loop and after-loop
+      ;; merging all the equivalent forms into the body.

       (do () ((or (null rbefore) (not (equal (car rbefore) (car rafter)))))
        (push (pop rbefore) main-body)
        (pop rafter))
       (unless rbefore (return (makebody)))
       (do () ((or (null rbefore) (not (equal (car rbefore) (car rafter)))))
        (push (pop rbefore) main-body)
        (pop rafter))
       (unless rbefore (return (makebody)))

-      ;; The first forms in RBEFORE & RAFTER (which are the chronologically
-      ;; last forms in the list) differ, therefore they cannot be moved
-      ;; into the main body. If everything that chronologically precedes
-      ;; them either differs or is equal but is okay to duplicate, we can
-      ;; just put all of rbefore in the prologue and all of rafter after
-      ;; the body. Otherwise, there is something that is not okay to
-      ;; duplicate, so it and everything chronologically after it in
-      ;; rbefore and rafter must go into the body, with a flag test to
-      ;; distinguish the first time around the loop from later times.
-      ;; What chronologically precedes the non-duplicatable form will
-      ;; be handled the next time around the outer loop.
+      ;; The first forms in RBEFORE & RAFTER (which are the
+      ;; chronologically last forms in the list) differ, therefore
+      ;; they cannot be moved into the main body. If everything that
+      ;; chronologically precedes them either differs or is equal but
+      ;; is okay to duplicate, we can just put all of rbefore in the
+      ;; prologue and all of rafter after the body. Otherwise, there
+      ;; is something that is not okay to duplicate, so it and
+      ;; everything chronologically after it in rbefore and rafter
+      ;; must go into the body, with a flag test to distinguish the
+      ;; first time around the loop from later times. What
+      ;; chronologically precedes the non-duplicatable form will be
+      ;; handled the next time around the outer loop.

       (do ((bb rbefore (cdr bb))
           (aa rafter (cdr aa))
           (lastdiff nil)
       (do ((bb rbefore (cdr bb))
           (aa rafter (cdr aa))
           (lastdiff nil)

@@ -685,7 +619,7 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
                   (push (pop rafter) then)
                   (when (eq rbefore (cdr lastdiff)) (return)))
                 (unless flagvar
                   (push (pop rafter) then)
                   (when (eq rbefore (cdr lastdiff)) (return)))
                 (unless flagvar

-                  (push `(setq ,(setq flagvar *loop-iteration-flag-variable*)
+                  (push `(setq ,(setq flagvar *loop-iteration-flag-var*)

                                t)
                         else))
                 (push `(if ,flagvar ,(pify (psimp then)) ,(pify (psimp else)))
                                t)
                         else))
                 (push `(if ,flagvar ,(pify (psimp then)) ,(pify (psimp else)))

@@ -703,9 +637,9 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
   (if (null expr) 0
       (let ((ans (estimate-code-size expr env)))
        (declare (fixnum ans))
   (if (null expr) 0
       (let ((ans (estimate-code-size expr env)))
        (declare (fixnum ans))

-       ;; @@@@ Use (DECLARATION-INFORMATION 'OPTIMIZE ENV) here to get an
-       ;; alist of optimize quantities back to help quantify how much code we
-       ;; are willing to duplicate.
+       ;; @@@@ Use (DECLARATION-INFORMATION 'OPTIMIZE ENV) here to
+       ;; get an alist of optimize quantities back to help quantify
+       ;; how much code we are willing to duplicate.

        ans)))
 
 (defvar *special-code-sizes*
        ans)))
 
 (defvar *special-code-sizes*

@@ -781,12 +715,10 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
                        (setq n (+ n (estimate-code-size-1 (cadr l) env) 1))))
                     ((eq fn 'go) 1)
                     ((eq fn 'function)
                        (setq n (+ n (estimate-code-size-1 (cadr l) env) 1))))
                     ((eq fn 'go) 1)
                     ((eq fn 'function)

-                     ;; This skirts the issue of implementationally-defined
-                     ;; lambda macros by recognizing CL function names and
-                     ;; nothing else.
-                     (if (or (symbolp (cadr x))
-                             (and (consp (cadr x)) (eq (caadr x) 'setf)))
+                     (if (sb!int:legal-fun-name-p (cadr x))

                          1
                          1

+                         ;; FIXME: This tag appears not to be present
+                         ;; anywhere.

                          (throw 'duplicatable-code-p nil)))
                     ((eq fn 'multiple-value-setq)
                      (f (length (second x)) (cddr x)))
                          (throw 'duplicatable-code-p nil)))
                     ((eq fn 'multiple-value-setq)
                      (f (length (second x)) (cddr x)))

@@ -809,10 +741,9 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
       ((eq l (cdr *loop-source-code*)) (nreverse new))))
 
 (defun loop-error (format-string &rest format-args)
       ((eq l (cdr *loop-source-code*)) (nreverse new))))
 
 (defun loop-error (format-string &rest format-args)

-  (error "~?~%current LOOP context:~{ ~S~}."
-        format-string
-        format-args
-        (loop-context)))
+  (error 'sb!int:simple-program-error
+        :format-control "~?~%current LOOP context:~{ ~S~}."
+        :format-arguments (list format-string format-args (loop-context))))

 
 (defun loop-warn (format-string &rest format-args)
   (warn "~?~%current LOOP context:~{ ~S~}."
 
 (defun loop-warn (format-string &rest format-args)
   (warn "~?~%current LOOP context:~{ ~S~}."

@@ -833,14 +764,38 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
                           specified-type required-type)))
        specified-type)))
 \f
                           specified-type required-type)))
        specified-type)))
 \f

+(defun subst-gensyms-for-nil (tree)
+  (declare (special *ignores*))
+  (cond
+    ((null tree) (car (push (gensym "LOOP-IGNORED-VAR-") *ignores*)))
+    ((atom tree) tree)
+    (t (cons (subst-gensyms-for-nil (car tree))
+            (subst-gensyms-for-nil (cdr tree))))))
+    
+(sb!int:defmacro-mundanely loop-destructuring-bind
+    (lambda-list arg-list &rest body)
+  (let ((*ignores* nil))
+    (declare (special *ignores*))
+    (let ((d-var-lambda-list (subst-gensyms-for-nil lambda-list)))
+      `(destructuring-bind ,d-var-lambda-list
+          ,arg-list
+        (declare (ignore ,@*ignores*))
+         ,@body))))
+
+(defun loop-build-destructuring-bindings (crocks forms)
+  (if crocks
+      `((loop-destructuring-bind ,(car crocks) ,(cadr crocks)
+        ,@(loop-build-destructuring-bindings (cddr crocks) forms)))
+      forms))
+

 (defun loop-translate (*loop-source-code*
                       *loop-macro-environment*
                       *loop-universe*)
   (let ((*loop-original-source-code* *loop-source-code*)
        (*loop-source-context* nil)
 (defun loop-translate (*loop-source-code*
                       *loop-macro-environment*
                       *loop-universe*)
   (let ((*loop-original-source-code* *loop-source-code*)
        (*loop-source-context* nil)

-       (*loop-iteration-variables* nil)
-       (*loop-variables* nil)
-       (*loop-named-variables* nil)
+       (*loop-iteration-vars* nil)
+       (*loop-vars* nil)
+       (*loop-named-vars* nil)

        (*loop-declarations* nil)
        (*loop-desetq-crocks* nil)
        (*loop-bind-stack* nil)
        (*loop-declarations* nil)
        (*loop-desetq-crocks* nil)
        (*loop-bind-stack* nil)

@@ -854,8 +809,8 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
        (*loop-after-epilogue* nil)
        (*loop-final-value-culprit* nil)
        (*loop-inside-conditional* nil)
        (*loop-after-epilogue* nil)
        (*loop-final-value-culprit* nil)
        (*loop-inside-conditional* nil)

-       (*loop-when-it-variable* nil)
-       (*loop-never-stepped-variable* nil)
+       (*loop-when-it-var* nil)
+       (*loop-never-stepped-var* nil)

        (*loop-names* nil)
        (*loop-collection-cruft* nil))
     (loop-iteration-driver)
        (*loop-names* nil)
        (*loop-collection-cruft* nil))
     (loop-iteration-driver)

@@ -867,9 +822,6 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
                     ,(nreverse *loop-after-body*)
                     ,(nreconc *loop-epilogue*
                               (nreverse *loop-after-epilogue*)))))
                     ,(nreverse *loop-after-body*)
                     ,(nreconc *loop-epilogue*
                               (nreverse *loop-after-epilogue*)))))

-      (do () (nil)
-       (setq answer `(block ,(pop *loop-names*) ,answer))
-       (unless *loop-names* (return nil)))

       (dolist (entry *loop-bind-stack*)
        (let ((vars (first entry))
              (dcls (second entry))
       (dolist (entry *loop-bind-stack*)
        (let ((vars (first entry))
              (dcls (second entry))

@@ -881,16 +833,13 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
            (let ((forms (list answer)))
              ;;(when crocks (push crocks forms))
              (when dcls (push `(declare ,@dcls) forms))
            (let ((forms (list answer)))
              ;;(when crocks (push crocks forms))
              (when dcls (push `(declare ,@dcls) forms))

-             (setq answer `(,(cond ((not vars) 'locally)
-                                   (*loop-destructuring-hooks*
-                                    (first *loop-destructuring-hooks*))
-                                   (t
-                                    'let))
+             (setq answer `(,(if vars 'let 'locally)

                             ,vars
                             ,vars

-                            ,@(if crocks
-                                  `((destructuring-bind ,@crocks
-                                        ,@forms))
-                                forms)))))))
+                            ,@(loop-build-destructuring-bindings crocks
+                                                                 forms)))))))
+      (do () (nil)
+       (setq answer `(block ,(pop *loop-names*) ,answer))
+       (unless *loop-names* (return nil)))

       answer)))
 
 (defun loop-iteration-driver ()
       answer)))
 
 (defun loop-iteration-driver ()

@@ -925,17 +874,25 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
       (pop *loop-source-code*)
       (loop-error "LOOP source code ran out when another token was expected.")))
 
       (pop *loop-source-code*)
       (loop-error "LOOP source code ran out when another token was expected.")))
 

-(defun loop-get-progn ()
-  (do ((forms (list (loop-pop-source)) (cons (loop-pop-source) forms))
-       (nextform (car *loop-source-code*) (car *loop-source-code*)))
-      ((atom nextform)
-       (if (null (cdr forms)) (car forms) (cons 'progn (nreverse forms))))))
-

 (defun loop-get-form ()
   (if *loop-source-code*
       (loop-pop-source)
       (loop-error "LOOP code ran out where a form was expected.")))
 
 (defun loop-get-form ()
   (if *loop-source-code*
       (loop-pop-source)
       (loop-error "LOOP code ran out where a form was expected.")))
 

+(defun loop-get-compound-form ()
+  (let ((form (loop-get-form)))
+    (unless (consp form)
+      (loop-error "A compound form was expected, but ~S found." form))
+    form))
+
+(defun loop-get-progn ()
+  (do ((forms (list (loop-get-compound-form))
+              (cons (loop-get-compound-form) forms))
+       (nextform (car *loop-source-code*)
+                 (car *loop-source-code*)))
+      ((atom nextform)
+       (if (null (cdr forms)) (car forms) (cons 'progn (nreverse forms))))))
+

 (defun loop-construct-return (form)
   `(return-from ,(car *loop-names*) ,form))
 
 (defun loop-construct-return (form)
   `(return-from ,(car *loop-names*) ,form))
 

@@ -948,43 +905,53 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
   (setq *loop-emitted-body* t)
   (loop-pseudo-body form))
 
   (setq *loop-emitted-body* t)
   (loop-pseudo-body form))
 

-(defun loop-emit-final-value (form)
-  (push (loop-construct-return form) *loop-after-epilogue*)
+(defun loop-emit-final-value (&optional (form nil form-supplied-p))
+  (when form-supplied-p
+    (push (loop-construct-return form) *loop-after-epilogue*))

   (when *loop-final-value-culprit*
   (when *loop-final-value-culprit*

-    (loop-warn "The LOOP clause is providing a value for the iteration,~@
-               however one was already established by a ~S clause."
+    (loop-warn "The LOOP clause is providing a value for the iteration;~@
+               however, one was already established by a ~S clause."

               *loop-final-value-culprit*))
   (setq *loop-final-value-culprit* (car *loop-source-context*)))
 
 (defun loop-disallow-conditional (&optional kwd)
   (when *loop-inside-conditional*
     (loop-error "~:[This LOOP~;The LOOP ~:*~S~] clause is not permitted inside a conditional." kwd)))
               *loop-final-value-culprit*))
   (setq *loop-final-value-culprit* (car *loop-source-context*)))
 
 (defun loop-disallow-conditional (&optional kwd)
   (when *loop-inside-conditional*
     (loop-error "~:[This LOOP~;The LOOP ~:*~S~] clause is not permitted inside a conditional." kwd)))

+
+(defun loop-disallow-anonymous-collectors ()
+  (when (find-if-not 'loop-collector-name *loop-collection-cruft*)
+    (loop-error "This LOOP clause is not permitted with anonymous collectors.")))
+
+(defun loop-disallow-aggregate-booleans ()
+  (when (loop-tmember *loop-final-value-culprit* '(always never thereis))
+    (loop-error "This anonymous collection LOOP clause is not permitted with aggregate booleans.")))

 \f
 ;;;; loop types
 
 \f
 ;;;; loop types
 

-(defun loop-typed-init (data-type)
+(defun loop-typed-init (data-type &optional step-var-p)

   (when (and data-type (sb!xc:subtypep data-type 'number))
     (if (or (sb!xc:subtypep data-type 'float)
            (sb!xc:subtypep data-type '(complex float)))
   (when (and data-type (sb!xc:subtypep data-type 'number))
     (if (or (sb!xc:subtypep data-type 'float)
            (sb!xc:subtypep data-type '(complex float)))

-       (coerce 0 data-type)
-       0)))
+       (coerce (if step-var-p 1 0) data-type)
+       (if step-var-p 1 0))))

 
 (defun loop-optional-type (&optional variable)
   ;; No variable specified implies that no destructuring is permissible.
   (and *loop-source-code* ; Don't get confused by NILs..
        (let ((z (car *loop-source-code*)))
         (cond ((loop-tequal z 'of-type)
 
 (defun loop-optional-type (&optional variable)
   ;; No variable specified implies that no destructuring is permissible.
   (and *loop-source-code* ; Don't get confused by NILs..
        (let ((z (car *loop-source-code*)))
         (cond ((loop-tequal z 'of-type)

-               ;; This is the syntactically unambigous form in that the form
-               ;; of the type specifier does not matter. Also, it is assumed
-               ;; that the type specifier is unambiguously, and without need
-               ;; of translation, a common lisp type specifier or pattern
-               ;; (matching the variable) thereof.
+               ;; This is the syntactically unambigous form in that
+               ;; the form of the type specifier does not matter.
+               ;; Also, it is assumed that the type specifier is
+               ;; unambiguously, and without need of translation, a
+               ;; common lisp type specifier or pattern (matching the
+               ;; variable) thereof.

                (loop-pop-source)
                (loop-pop-source))
 
               ((symbolp z)
                (loop-pop-source)
                (loop-pop-source))
 
               ((symbolp z)

-               ;; This is the (sort of) "old" syntax, even though we didn't
-               ;; used to support all of these type symbols.
+               ;; This is the (sort of) "old" syntax, even though we
+               ;; didn't used to support all of these type symbols.

                (let ((type-spec (or (gethash z
                                              (loop-universe-type-symbols
                                               *loop-universe*))
                (let ((type-spec (or (gethash z
                                              (loop-universe-type-symbols
                                               *loop-universe*))

@@ -995,11 +962,12 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
                    (loop-pop-source)
                    type-spec)))
               (t
                    (loop-pop-source)
                    type-spec)))
               (t

-               ;; This is our sort-of old syntax. But this is only valid for
-               ;; when we are destructuring, so we will be compulsive (should
-               ;; we really be?) and require that we in fact be doing variable
-               ;; destructuring here. We must translate the old keyword
-               ;; pattern typespec into a fully-specified pattern of real type
+               ;; This is our sort-of old syntax. But this is only
+               ;; valid for when we are destructuring, so we will be
+               ;; compulsive (should we really be?) and require that
+               ;; we in fact be doing variable destructuring here. We
+               ;; must translate the old keyword pattern typespec
+               ;; into a fully-specified pattern of real type

                ;; specifiers here.
                (if (consp variable)
                    (unless (consp z)
                ;; specifiers here.
                (if (consp variable)
                    (unless (consp z)

@@ -1038,83 +1006,90 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
 ;;;; loop variables
 
 (defun loop-bind-block ()
 ;;;; loop variables
 
 (defun loop-bind-block ()

-  (when (or *loop-variables* *loop-declarations* *loop-wrappers*)
-    (push (list (nreverse *loop-variables*)
+  (when (or *loop-vars* *loop-declarations* *loop-wrappers*)
+    (push (list (nreverse *loop-vars*)

                *loop-declarations*
                *loop-desetq-crocks*
                *loop-wrappers*)
          *loop-bind-stack*)
                *loop-declarations*
                *loop-desetq-crocks*
                *loop-wrappers*)
          *loop-bind-stack*)

-    (setq *loop-variables* nil
+    (setq *loop-vars* nil

          *loop-declarations* nil
          *loop-desetq-crocks* nil
          *loop-wrappers* nil)))
 
          *loop-declarations* nil
          *loop-desetq-crocks* nil
          *loop-wrappers* nil)))
 

-(defun loop-make-variable (name initialization dtype
-                          &optional iteration-variable-p)
+(defun loop-var-p (name)
+  (do ((entry *loop-bind-stack* (cdr entry)))
+      (nil)
+    (cond
+      ((null entry) (return nil))
+      ((assoc name (caar entry) :test #'eq) (return t)))))
+
+(defun loop-make-var (name initialization dtype &optional iteration-var-p step-var-p)

   (cond ((null name)
   (cond ((null name)

-        (cond ((not (null initialization))
-               (push (list (setq name (loop-gentemp 'loop-ignore-))
-                           initialization)
-                     *loop-variables*)
-               (push `(ignore ,name) *loop-declarations*))))
+        (setq name (gensym "LOOP-IGNORE-"))
+        (push (list name initialization) *loop-vars*)
+        (if (null initialization)
+            (push `(ignore ,name) *loop-declarations*)
+            (loop-declare-var name dtype)))

        ((atom name)
        ((atom name)

-        (cond (iteration-variable-p
-               (if (member name *loop-iteration-variables*)
+        (cond (iteration-var-p
+               (if (member name *loop-iteration-vars*)

                    (loop-error "duplicated LOOP iteration variable ~S" name)
                    (loop-error "duplicated LOOP iteration variable ~S" name)

-                   (push name *loop-iteration-variables*)))
-              ((assoc name *loop-variables*)
+                   (push name *loop-iteration-vars*)))
+              ((assoc name *loop-vars*)

                (loop-error "duplicated variable ~S in LOOP parallel binding"
                            name)))
         (unless (symbolp name)
           (loop-error "bad variable ~S somewhere in LOOP" name))
                (loop-error "duplicated variable ~S in LOOP parallel binding"
                            name)))
         (unless (symbolp name)
           (loop-error "bad variable ~S somewhere in LOOP" name))

-        (loop-declare-variable name dtype)
+        (loop-declare-var name dtype step-var-p)

         ;; We use ASSOC on this list to check for duplications (above),
         ;; so don't optimize out this list:
         ;; We use ASSOC on this list to check for duplications (above),
         ;; so don't optimize out this list:

-        (push (list name (or initialization (loop-typed-init dtype)))
-              *loop-variables*))
+        (push (list name (or initialization (loop-typed-init dtype step-var-p)))
+              *loop-vars*))

        (initialization
        (initialization

-        (cond (*loop-destructuring-hooks*
-               (loop-declare-variable name dtype)
-               (push (list name initialization) *loop-variables*))
-              (t (let ((newvar (loop-gentemp 'loop-destructure-)))
-                   (push (list newvar initialization) *loop-variables*)
-                   ;; *LOOP-DESETQ-CROCKS* gathered in reverse order.
-                   (setq *loop-desetq-crocks*
-                     (list* name newvar *loop-desetq-crocks*))))))
+        (let ((newvar (gensym "LOOP-DESTRUCTURE-")))
+           (loop-declare-var name dtype)
+           (push (list newvar initialization) *loop-vars*)
+           ;; *LOOP-DESETQ-CROCKS* gathered in reverse order.
+           (setq *loop-desetq-crocks*
+                 (list* name newvar *loop-desetq-crocks*))))

        (t (let ((tcar nil) (tcdr nil))
             (if (atom dtype) (setq tcar (setq tcdr dtype))
                 (setq tcar (car dtype) tcdr (cdr dtype)))
        (t (let ((tcar nil) (tcdr nil))
             (if (atom dtype) (setq tcar (setq tcdr dtype))
                 (setq tcar (car dtype) tcdr (cdr dtype)))

-            (loop-make-variable (car name) nil tcar iteration-variable-p)
-            (loop-make-variable (cdr name) nil tcdr iteration-variable-p))))
+            (loop-make-var (car name) nil tcar iteration-var-p)
+            (loop-make-var (cdr name) nil tcdr iteration-var-p))))

   name)
 
   name)
 

-(defun loop-make-iteration-variable (name initialization dtype)
-  (loop-make-variable name initialization dtype t))
+(defun loop-make-iteration-var (name initialization dtype)
+  (loop-make-var name initialization dtype t))

 
 

-(defun loop-declare-variable (name dtype)
+(defun loop-declare-var (name dtype &optional step-var-p)

   (cond ((or (null name) (null dtype) (eq dtype t)) nil)
        ((symbolp name)
         (unless (sb!xc:subtypep t dtype)
   (cond ((or (null name) (null dtype) (eq dtype t)) nil)
        ((symbolp name)
         (unless (sb!xc:subtypep t dtype)

-          (let ((dtype (let ((init (loop-typed-init dtype)))
+          (let ((dtype (let ((init (loop-typed-init dtype step-var-p)))

                          (if (sb!xc:typep init dtype)
                              dtype
                              `(or (member ,init) ,dtype)))))
             (push `(type ,dtype ,name) *loop-declarations*))))
        ((consp name)
         (cond ((consp dtype)
                          (if (sb!xc:typep init dtype)
                              dtype
                              `(or (member ,init) ,dtype)))))
             (push `(type ,dtype ,name) *loop-declarations*))))
        ((consp name)
         (cond ((consp dtype)

-               (loop-declare-variable (car name) (car dtype))
-               (loop-declare-variable (cdr name) (cdr dtype)))
-              (t (loop-declare-variable (car name) dtype)
-                 (loop-declare-variable (cdr name) dtype))))
+               (loop-declare-var (car name) (car dtype))
+               (loop-declare-var (cdr name) (cdr dtype)))
+              (t (loop-declare-var (car name) dtype)
+                 (loop-declare-var (cdr name) dtype))))

        (t (error "invalid LOOP variable passed in: ~S" name))))
 
 (defun loop-maybe-bind-form (form data-type)
   (if (loop-constantp form)
       form
        (t (error "invalid LOOP variable passed in: ~S" name))))
 
 (defun loop-maybe-bind-form (form data-type)
   (if (loop-constantp form)
       form

-      (loop-make-variable (loop-gentemp 'loop-bind-) form data-type)))
+      (loop-make-var (gensym "LOOP-BIND-") form data-type)))

 \f
 (defun loop-do-if (for negatep)
 \f
 (defun loop-do-if (for negatep)

-  (let ((form (loop-get-form)) (*loop-inside-conditional* t) (it-p nil))
+  (let ((form (loop-get-form))
+       (*loop-inside-conditional* t)
+       (it-p nil)
+       (first-clause-p t))

     (flet ((get-clause (for)
             (do ((body nil)) (nil)
               (let ((key (car *loop-source-code*)) (*loop-body* nil) data)
     (flet ((get-clause (for)
             (do ((body nil)) (nil)
               (let ((key (car *loop-source-code*)) (*loop-body* nil) data)

@@ -1124,11 +1099,12 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
                          key for))
                       (t (setq *loop-source-context* *loop-source-code*)
                          (loop-pop-source)
                          key for))
                       (t (setq *loop-source-context* *loop-source-code*)
                          (loop-pop-source)

-                         (when (loop-tequal (car *loop-source-code*) 'it)
+                         (when (and (loop-tequal (car *loop-source-code*) 'it)
+                                    first-clause-p)

                            (setq *loop-source-code*
                                  (cons (or it-p
                                            (setq it-p
                            (setq *loop-source-code*
                                  (cons (or it-p
                                            (setq it-p

-                                                 (loop-when-it-variable)))
+                                                 (loop-when-it-var)))

                                        (cdr *loop-source-code*))))
                          (cond ((or (not (setq data (loop-lookup-keyword
                                                       key (loop-universe-keywords *loop-universe*))))
                                        (cdr *loop-source-code*))))
                          (cond ((or (not (setq data (loop-lookup-keyword
                                                       key (loop-universe-keywords *loop-universe*))))

@@ -1139,6 +1115,7 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
                                   "~S does not introduce a LOOP clause that can follow ~S."
                                   key for))
                                (t (setq body (nreconc *loop-body* body)))))))
                                   "~S does not introduce a LOOP clause that can follow ~S."
                                   key for))
                                (t (setq body (nreconc *loop-body* body)))))))

+              (setq first-clause-p nil)

               (if (loop-tequal (car *loop-source-code*) :and)
                   (loop-pop-source)
                   (return (if (cdr body)
               (if (loop-tequal (car *loop-source-code*) :and)
                   (loop-pop-source)
                   (return (if (cdr body)

@@ -1176,10 +1153,10 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
     (when *loop-names*
       (loop-error "You may only use one NAMED clause in your loop: NAMED ~S ... NAMED ~S."
                  (car *loop-names*) name))
     (when *loop-names*
       (loop-error "You may only use one NAMED clause in your loop: NAMED ~S ... NAMED ~S."
                  (car *loop-names*) name))

-    (setq *loop-names* (list name nil))))
+    (setq *loop-names* (list name))))

 
 (defun loop-do-return ()
 
 (defun loop-do-return ()

-  (loop-pseudo-body (loop-construct-return (loop-get-form))))
+  (loop-emit-body (loop-construct-return (loop-get-form))))

 \f
 ;;;; value accumulation: LIST
 
 \f
 ;;;; value accumulation: LIST
 

@@ -1201,11 +1178,15 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
                (loop-pop-source))))
     (when (not (symbolp name))
       (loop-error "The value accumulation recipient name, ~S, is not a symbol." name))
                (loop-pop-source))))
     (when (not (symbolp name))
       (loop-error "The value accumulation recipient name, ~S, is not a symbol." name))

+    (unless name
+      (loop-disallow-aggregate-booleans))

     (unless dtype
       (setq dtype (or (loop-optional-type) default-type)))
     (let ((cruft (find (the symbol name) *loop-collection-cruft*
                       :key #'loop-collector-name)))
       (cond ((not cruft)
     (unless dtype
       (setq dtype (or (loop-optional-type) default-type)))
     (let ((cruft (find (the symbol name) *loop-collection-cruft*
                       :key #'loop-collector-name)))
       (cond ((not cruft)

+            (when (and name (loop-var-p name))
+              (loop-error "Variable ~S in INTO clause is a duplicate" name))

             (push (setq cruft (make-loop-collector
                                 :name name :class class
                                 :history (list collector) :dtype dtype))
             (push (setq cruft (make-loop-collector
                                 :name name :class class
                                 :history (list collector) :dtype dtype))

@@ -1231,8 +1212,8 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
     (let ((tempvars (loop-collector-tempvars lc)))
       (unless tempvars
        (setf (loop-collector-tempvars lc)
     (let ((tempvars (loop-collector-tempvars lc)))
       (unless tempvars
        (setf (loop-collector-tempvars lc)

-             (setq tempvars (list* (loop-gentemp 'loop-list-head-)
-                                   (loop-gentemp 'loop-list-tail-)
+             (setq tempvars (list* (gensym "LOOP-LIST-HEAD-")
+                                   (gensym "LOOP-LIST-TAIL-")

                                    (and (loop-collector-name lc)
                                         (list (loop-collector-name lc))))))
        (push `(with-loop-list-collection-head ,tempvars) *loop-wrappers*)
                                    (and (loop-collector-name lc)
                                         (list (loop-collector-name lc))))))
        (push `(with-loop-list-collection-head ,tempvars) *loop-wrappers*)

@@ -1255,9 +1236,9 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
     (let ((tempvars (loop-collector-tempvars lc)))
       (unless tempvars
        (setf (loop-collector-tempvars lc)
     (let ((tempvars (loop-collector-tempvars lc)))
       (unless tempvars
        (setf (loop-collector-tempvars lc)

-             (setq tempvars (list (loop-make-variable
+             (setq tempvars (list (loop-make-var

                                     (or (loop-collector-name lc)
                                     (or (loop-collector-name lc)

-                                        (loop-gentemp 'loop-sum-))
+                                        (gensym "LOOP-SUM-"))

                                     nil (loop-collector-dtype lc)))))
        (unless (loop-collector-name lc)
          (loop-emit-final-value (car (loop-collector-tempvars lc)))))
                                     nil (loop-collector-dtype lc)))))
        (unless (loop-collector-name lc)
          (loop-emit-final-value (car (loop-collector-tempvars lc)))))

@@ -1265,25 +1246,21 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
        (if (eq specifically 'count)
            `(when ,form
               (setq ,(car tempvars)
        (if (eq specifically 'count)
            `(when ,form
               (setq ,(car tempvars)

-                    ,(hide-variable-reference t
-                                              (car tempvars)
-                                              `(1+ ,(car tempvars)))))
+                    (1+ ,(car tempvars))))

            `(setq ,(car tempvars)
            `(setq ,(car tempvars)

-                  (+ ,(hide-variable-reference t
-                                               (car tempvars)
-                                               (car tempvars))
+                  (+ ,(car tempvars)

                      ,form)))))))
 
 (defun loop-maxmin-collection (specifically)
   (multiple-value-bind (lc form)
                      ,form)))))))
 
 (defun loop-maxmin-collection (specifically)
   (multiple-value-bind (lc form)

-      (loop-get-collection-info specifically 'maxmin *loop-real-data-type*)
-    (loop-check-data-type (loop-collector-dtype lc) *loop-real-data-type*)
+      (loop-get-collection-info specifically 'maxmin 'real)
+    (loop-check-data-type (loop-collector-dtype lc) 'real)

     (let ((data (loop-collector-data lc)))
       (unless data
        (setf (loop-collector-data lc)
              (setq data (make-loop-minimax
                           (or (loop-collector-name lc)
     (let ((data (loop-collector-data lc)))
       (unless data
        (setf (loop-collector-data lc)
              (setq data (make-loop-minimax
                           (or (loop-collector-name lc)

-                              (loop-gentemp 'loop-maxmin-))
+                              (gensym "LOOP-MAXMIN-"))

                           (loop-collector-dtype lc))))
        (unless (loop-collector-name lc)
          (loop-emit-final-value (loop-minimax-answer-variable data))))
                           (loop-collector-dtype lc))))
        (unless (loop-collector-name lc)
          (loop-emit-final-value (loop-minimax-answer-variable data))))

@@ -1301,6 +1278,7 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
 (defun loop-do-always (restrictive negate)
   (let ((form (loop-get-form)))
     (when restrictive (loop-disallow-conditional))
 (defun loop-do-always (restrictive negate)
   (let ((form (loop-get-form)))
     (when restrictive (loop-disallow-conditional))

+    (loop-disallow-anonymous-collectors)

     (loop-emit-body `(,(if negate 'when 'unless) ,form
                      ,(loop-construct-return nil)))
     (loop-emit-final-value t)))
     (loop-emit-body `(,(if negate 'when 'unless) ,form
                      ,(loop-construct-return nil)))
     (loop-emit-final-value t)))

@@ -1310,13 +1288,31 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
 ;;; Under ANSI this is not permitted to appear under conditionalization.
 (defun loop-do-thereis (restrictive)
   (when restrictive (loop-disallow-conditional))
 ;;; Under ANSI this is not permitted to appear under conditionalization.
 (defun loop-do-thereis (restrictive)
   (when restrictive (loop-disallow-conditional))

-  (loop-emit-body `(when (setq ,(loop-when-it-variable) ,(loop-get-form))
-                    ,(loop-construct-return *loop-when-it-variable*))))
+  (loop-disallow-anonymous-collectors)
+  (loop-emit-final-value)
+  (loop-emit-body `(when (setq ,(loop-when-it-var) ,(loop-get-form))
+                   ,(loop-construct-return *loop-when-it-var*))))

 \f
 (defun loop-do-while (negate kwd &aux (form (loop-get-form)))
   (loop-disallow-conditional kwd)
   (loop-pseudo-body `(,(if negate 'when 'unless) ,form (go end-loop))))
 
 \f
 (defun loop-do-while (negate kwd &aux (form (loop-get-form)))
   (loop-disallow-conditional kwd)
   (loop-pseudo-body `(,(if negate 'when 'unless) ,form (go end-loop))))
 

+(defun loop-do-repeat ()
+  (loop-disallow-conditional :repeat)
+  (let ((form (loop-get-form))
+       (type 'integer))
+    (let ((var (loop-make-var (gensym "LOOP-REPEAT-") `(ceiling ,form) type)))
+      (push `(if (<= ,var 0) (go end-loop) (decf ,var)) *loop-before-loop*)
+      (push `(if (<= ,var 0) (go end-loop) (decf ,var)) *loop-after-body*)
+      ;; FIXME: What should
+      ;;   (loop count t into a
+      ;;         repeat 3
+      ;;         count t into b
+      ;;         finally (return (list a b)))
+      ;; return: (3 3) or (4 3)? PUSHes above are for the former
+      ;; variant, L-P-B below for the latter.
+      #+nil (loop-pseudo-body `(when (minusp (decf ,var)) (go end-loop))))))
+

 (defun loop-do-with ()
   (loop-disallow-conditional :with)
   (do ((var) (val) (dtype)) (nil)
 (defun loop-do-with ()
   (loop-disallow-conditional :with)
   (do ((var) (val) (dtype)) (nil)

@@ -1326,7 +1322,9 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
                     (loop-pop-source)
                     (loop-get-form))
                    (t nil)))
                     (loop-pop-source)
                     (loop-get-form))
                    (t nil)))

-    (loop-make-variable var val dtype)
+    (when (and var (loop-var-p var))
+      (loop-error "Variable ~S has already been used" var))
+    (loop-make-var var val dtype)

     (if (loop-tequal (car *loop-source-code*) :and)
        (loop-pop-source)
        (return (loop-bind-block)))))
     (if (loop-tequal (car *loop-source-code*) :and)
        (loop-pop-source)
        (return (loop-bind-block)))))

@@ -1418,40 +1416,20 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
                  keyword))
     (apply (car tem) var first-arg data-type (cdr tem))))
 
                  keyword))
     (apply (car tem) var first-arg data-type (cdr tem))))
 

-(defun loop-do-repeat ()
-  (let ((form (loop-get-form))
-       (type (loop-check-data-type (loop-optional-type)
-                                   *loop-real-data-type*)))
-    (when (and (consp form)
-              (eq (car form) 'the)
-              (sb!xc:subtypep (second form) type))
-      (setq type (second form)))
-    (multiple-value-bind (number constantp value)
-       (loop-constant-fold-if-possible form type)
-      (cond ((and constantp (<= value 1)) `(t () () () ,(<= value 0) () () ()))
-           (t (let ((var (loop-make-variable (loop-gentemp 'loop-repeat-)
-                                             number
-                                             type)))
-                (if constantp
-                    `((not (plusp (setq ,var (1- ,var))))
-                      () () () () () () ())
-                    `((minusp (setq ,var (1- ,var)))
-                      () () ()))))))))
-
-(defun loop-when-it-variable ()
-  (or *loop-when-it-variable*
-      (setq *loop-when-it-variable*
-           (loop-make-variable (loop-gentemp 'loop-it-) nil nil))))
+(defun loop-when-it-var ()
+  (or *loop-when-it-var*
+      (setq *loop-when-it-var*
+           (loop-make-var (gensym "LOOP-IT-") nil nil))))

 \f
 ;;;; various FOR/AS subdispatches
 
 \f
 ;;;; various FOR/AS subdispatches
 

-;;; ANSI "FOR x = y [THEN z]" is sort of like the old Genera one when the THEN
-;;; is omitted (other than being more stringent in its placement), and like the
-;;; old "FOR x FIRST y THEN z" when the THEN is present. I.e., the first
-;;; initialization occurs in the loop body (first-step), not in the variable
-;;; binding phase.
+;;; ANSI "FOR x = y [THEN z]" is sort of like the old Genera one when
+;;; the THEN is omitted (other than being more stringent in its
+;;; placement), and like the old "FOR x FIRST y THEN z" when the THEN
+;;; is present. I.e., the first initialization occurs in the loop body
+;;; (first-step), not in the variable binding phase.

 (defun loop-ansi-for-equals (var val data-type)
 (defun loop-ansi-for-equals (var val data-type)

-  (loop-make-iteration-variable var nil data-type)
+  (loop-make-iteration-var var nil data-type)

   (cond ((loop-tequal (car *loop-source-code*) :then)
         ;; Then we are the same as "FOR x FIRST y THEN z".
         (loop-pop-source)
   (cond ((loop-tequal (car *loop-source-code*) :then)
         ;; Then we are the same as "FOR x FIRST y THEN z".
         (loop-pop-source)

@@ -1461,23 +1439,23 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
         `(() (,var ,val) () ()))))
 
 (defun loop-for-across (var val data-type)
         `(() (,var ,val) () ()))))
 
 (defun loop-for-across (var val data-type)

-  (loop-make-iteration-variable var nil data-type)
-  (let ((vector-var (loop-gentemp 'loop-across-vector-))
-       (index-var (loop-gentemp 'loop-across-index-)))
+  (loop-make-iteration-var var nil data-type)
+  (let ((vector-var (gensym "LOOP-ACROSS-VECTOR-"))
+       (index-var (gensym "LOOP-ACROSS-INDEX-")))

     (multiple-value-bind (vector-form constantp vector-value)
        (loop-constant-fold-if-possible val 'vector)
     (multiple-value-bind (vector-form constantp vector-value)
        (loop-constant-fold-if-possible val 'vector)

-      (loop-make-variable
+      (loop-make-var

        vector-var vector-form
        (if (and (consp vector-form) (eq (car vector-form) 'the))
            (cadr vector-form)
            'vector))
        vector-var vector-form
        (if (and (consp vector-form) (eq (car vector-form) 'the))
            (cadr vector-form)
            'vector))

-      (loop-make-variable index-var 0 'fixnum)
+      (loop-make-var index-var 0 'fixnum)

       (let* ((length 0)
             (length-form (cond ((not constantp)
       (let* ((length 0)
             (length-form (cond ((not constantp)

-                                (let ((v (loop-gentemp 'loop-across-limit-)))
+                                (let ((v (gensym "LOOP-ACROSS-LIMIT-")))

                                   (push `(setq ,v (length ,vector-var))
                                         *loop-prologue*)
                                   (push `(setq ,v (length ,vector-var))
                                         *loop-prologue*)

-                                  (loop-make-variable v 0 'fixnum)))
+                                  (loop-make-var v 0 'fixnum)))

                                (t (setq length (length vector-value)))))
             (first-test `(>= ,index-var ,length-form))
             (other-test first-test)
                                (t (setq length (length vector-value)))))
             (first-test `(>= ,index-var ,length-form))
             (other-test first-test)

@@ -1495,9 +1473,9 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
 ;;;; list iteration
 
 (defun loop-list-step (listvar)
 ;;;; list iteration
 
 (defun loop-list-step (listvar)

-  ;; We are not equipped to analyze whether 'FOO is the same as #'FOO here in
-  ;; any sensible fashion, so let's give an obnoxious warning whenever 'FOO is
-  ;; used as the stepping function.
+  ;; We are not equipped to analyze whether 'FOO is the same as #'FOO
+  ;; here in any sensible fashion, so let's give an obnoxious warning
+  ;; whenever 'FOO is used as the stepping function.

   ;;
   ;; While a Discerning Compiler may deal intelligently with
   ;; (FUNCALL 'FOO ...), not recognizing FOO may defeat some LOOP
   ;;
   ;; While a Discerning Compiler may deal intelligently with
   ;; (FUNCALL 'FOO ...), not recognizing FOO may defeat some LOOP

@@ -1512,9 +1490,7 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
          ((and (consp stepper) (eq (car stepper) 'function))
           (list (cadr stepper) listvar))
          (t
          ((and (consp stepper) (eq (car stepper) 'function))
           (list (cadr stepper) listvar))
          (t

-          `(funcall ,(loop-make-variable (loop-gentemp 'loop-fn-)
-                                         stepper
-                                         'function)
+          `(funcall ,(loop-make-var (gensym "LOOP-FN-") stepper 'function)

                     ,listvar)))))
 
 (defun loop-for-on (var val data-type)
                     ,listvar)))))
 
 (defun loop-for-on (var val data-type)

@@ -1522,24 +1498,22 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
       (loop-constant-fold-if-possible val)
     (let ((listvar var))
       (cond ((and var (symbolp var))
       (loop-constant-fold-if-possible val)
     (let ((listvar var))
       (cond ((and var (symbolp var))

-            (loop-make-iteration-variable var list data-type))
-           (t (loop-make-variable (setq listvar (loop-gentemp)) list 'list)
-              (loop-make-iteration-variable var nil data-type)))
+            (loop-make-iteration-var var list data-type))
+           (t (loop-make-var (setq listvar (gensym)) list 'list)
+              (loop-make-iteration-var var nil data-type)))

       (let ((list-step (loop-list-step listvar)))
        (let* ((first-endtest
       (let ((list-step (loop-list-step listvar)))
        (let* ((first-endtest

-               (hide-variable-reference
-                (eq var listvar)
-                listvar
-                ;; the following should use `atom' instead of `endp', per
-                ;; [bug2428]
-                `(atom ,listvar)))
+               ;; mysterious comment from original CMU CL sources:
+               ;;   the following should use `atom' instead of `endp',
+               ;;   per [bug2428]
+               `(atom ,listvar))

               (other-endtest first-endtest))
          (when (and constantp (listp list-value))
            (setq first-endtest (null list-value)))
          (cond ((eq var listvar)
               (other-endtest first-endtest))
          (when (and constantp (listp list-value))
            (setq first-endtest (null list-value)))
          (cond ((eq var listvar)

-                ;; Contour of the loop is different because we use the user's
-                ;; variable...
-                `(() (,listvar ,(hide-variable-reference t listvar list-step))
+                ;; The contour of the loop is different because we
+                ;; use the user's variable...
+                `(() (,listvar ,list-step)

                   ,other-endtest () () () ,first-endtest ()))
                (t (let ((step `(,var ,listvar))
                         (pseudo `(,listvar ,list-step)))
                   ,other-endtest () () () ,first-endtest ()))
                (t (let ((step `(,var ,listvar))
                         (pseudo `(,listvar ,list-step)))

@@ -1550,9 +1524,9 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
 (defun loop-for-in (var val data-type)
   (multiple-value-bind (list constantp list-value)
       (loop-constant-fold-if-possible val)
 (defun loop-for-in (var val data-type)
   (multiple-value-bind (list constantp list-value)
       (loop-constant-fold-if-possible val)

-    (let ((listvar (loop-gentemp 'loop-list-)))
-      (loop-make-iteration-variable var nil data-type)
-      (loop-make-variable listvar list 'list)
+    (let ((listvar (gensym "LOOP-LIST-")))
+      (loop-make-iteration-var var nil data-type)
+      (loop-make-var listvar list 'list)

       (let ((list-step (loop-list-step listvar)))
        (let* ((first-endtest `(endp ,listvar))
               (other-endtest first-endtest)
       (let ((list-step (loop-list-step listvar)))
        (let* ((first-endtest `(endp ,listvar))
               (other-endtest first-endtest)

@@ -1593,7 +1567,7 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
       (setf (gethash (symbol-name name) ht) lp))
     lp))
 \f
       (setf (gethash (symbol-name name) ht) lp))
     lp))
 \f

-;;; Note:  path functions are allowed to use loop-make-variable, hack
+;;; Note: Path functions are allowed to use LOOP-MAKE-VAR, hack

 ;;; the prologue, etc.
 (defun loop-for-being (var val data-type)
   ;; FOR var BEING each/the pathname prep-phrases using-stuff... each/the =
 ;;; the prologue, etc.
 (defun loop-for-being (var val data-type)
   ;; FOR var BEING each/the pathname prep-phrases using-stuff... each/the =

@@ -1633,30 +1607,30 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
       (setq stuff (if inclusive
                      (apply fun var data-type preps :inclusive t user-data)
                      (apply fun var data-type preps user-data))))
       (setq stuff (if inclusive
                      (apply fun var data-type preps :inclusive t user-data)
                      (apply fun var data-type preps user-data))))

-    (when *loop-named-variables*
-      (loop-error "Unused USING variables: ~S." *loop-named-variables*))
-    ;; STUFF is now (bindings prologue-forms . stuff-to-pass-back). Protect the
-    ;; system from the user and the user from himself.
+    (when *loop-named-vars*
+      (loop-error "Unused USING vars: ~S." *loop-named-vars*))
+    ;; STUFF is now (bindings prologue-forms . stuff-to-pass-back).
+    ;; Protect the system from the user and the user from himself.

     (unless (member (length stuff) '(6 10))
       (loop-error "Value passed back by LOOP iteration path function for path ~S has invalid length."
                  path))
     (do ((l (car stuff) (cdr l)) (x)) ((null l))
       (if (atom (setq x (car l)))
     (unless (member (length stuff) '(6 10))
       (loop-error "Value passed back by LOOP iteration path function for path ~S has invalid length."
                  path))
     (do ((l (car stuff) (cdr l)) (x)) ((null l))
       (if (atom (setq x (car l)))

-         (loop-make-iteration-variable x nil nil)
-         (loop-make-iteration-variable (car x) (cadr x) (caddr x))))
+         (loop-make-iteration-var x nil nil)
+         (loop-make-iteration-var (car x) (cadr x) (caddr x))))

     (setq *loop-prologue* (nconc (reverse (cadr stuff)) *loop-prologue*))
     (cddr stuff)))
 \f
     (setq *loop-prologue* (nconc (reverse (cadr stuff)) *loop-prologue*))
     (cddr stuff)))
 \f

-(defun named-variable (name)
-  (let ((tem (loop-tassoc name *loop-named-variables*)))
+(defun loop-named-var (name)
+  (let ((tem (loop-tassoc name *loop-named-vars*)))

     (declare (list tem))
     (declare (list tem))

-    (cond ((null tem) (values (loop-gentemp) nil))
-         (t (setq *loop-named-variables* (delete tem *loop-named-variables*))
+    (cond ((null tem) (values (gensym) nil))
+         (t (setq *loop-named-vars* (delete tem *loop-named-vars*))

             (values (cdr tem) t)))))
 
 (defun loop-collect-prepositional-phrases (preposition-groups
                                           &optional
             (values (cdr tem) t)))))
 
 (defun loop-collect-prepositional-phrases (preposition-groups
                                           &optional

-                                          USING-allowed
+                                          using-allowed

                                           initial-phrases)
   (flet ((in-group-p (x group) (car (loop-tmember x group))))
     (do ((token nil)
                                           initial-phrases)
   (flet ((in-group-p (x group) (car (loop-tmember x group))))
     (do ((token nil)

@@ -1664,9 +1638,9 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
         (this-group nil nil)
         (this-prep nil nil)
         (disallowed-prepositions
         (this-group nil nil)
         (this-prep nil nil)
         (disallowed-prepositions

-          (mapcan #'(lambda (x)
-                      (copy-list
-                        (find (car x) preposition-groups :test #'in-group-p)))
+          (mapcan (lambda (x)
+                    (copy-list
+                     (find (car x) preposition-groups :test #'in-group-p)))

                   initial-phrases))
         (used-prepositions (mapcar #'car initial-phrases)))
        ((null *loop-source-code*) (nreverse prepositional-phrases))
                   initial-phrases))
         (used-prepositions (mapcar #'car initial-phrases)))
        ((null *loop-source-code*) (nreverse prepositional-phrases))

@@ -1687,22 +1661,16 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
                                         (cons this-group used-prepositions)))
             (loop-pop-source)
             (push (list this-prep (loop-get-form)) prepositional-phrases))
                                         (cons this-group used-prepositions)))
             (loop-pop-source)
             (push (list this-prep (loop-get-form)) prepositional-phrases))

-           ((and USING-allowed (loop-tequal token 'using))
+           ((and using-allowed (loop-tequal token 'using))

             (loop-pop-source)
             (do ((z (loop-pop-source) (loop-pop-source)) (tem)) (nil)
             (loop-pop-source)
             (do ((z (loop-pop-source) (loop-pop-source)) (tem)) (nil)

-              (when (or (atom z)
-                        (atom (cdr z))
-                        (not (null (cddr z)))
-                        (not (symbolp (car z)))
-                        (and (cadr z) (not (symbolp (cadr z)))))
-                (loop-error "~S bad variable pair in path USING phrase" z))

               (when (cadr z)
               (when (cadr z)

-                (if (setq tem (loop-tassoc (car z) *loop-named-variables*))
+                (if (setq tem (loop-tassoc (car z) *loop-named-vars*))

                     (loop-error
                       "The variable substitution for ~S occurs twice in a USING phrase,~@
                        with ~S and ~S."
                       (car z) (cadr z) (cadr tem))
                     (loop-error
                       "The variable substitution for ~S occurs twice in a USING phrase,~@
                        with ~S and ~S."
                       (car z) (cadr z) (cadr tem))

-                    (push (cons (car z) (cadr z)) *loop-named-variables*)))
+                    (push (cons (car z) (cadr z)) *loop-named-vars*)))

               (when (or (null *loop-source-code*)
                         (symbolp (car *loop-source-code*)))
                 (return nil))))
               (when (or (null *loop-source-code*)
                         (symbolp (car *loop-source-code*)))
                 (return nil))))

@@ -1710,12 +1678,12 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
 \f
 ;;;; master sequencer function
 
 \f
 ;;;; master sequencer function
 

-(defun loop-sequencer (indexv indexv-type indexv-user-specified-p
-                         variable variable-type
-                         sequence-variable sequence-type
-                         step-hack default-top
-                         prep-phrases)
-   (let ((endform nil) ; Form (constant or variable) with limit value
+(defun loop-sequencer (indexv indexv-type 
+                      variable variable-type
+                      sequence-variable sequence-type
+                      step-hack default-top
+                      prep-phrases)
+   (let ((endform nil) ; form (constant or variable) with limit value

         (sequencep nil) ; T if sequence arg has been provided
         (testfn nil) ; endtest function
         (test nil) ; endtest form
         (sequencep nil) ; T if sequence arg has been provided
         (testfn nil) ; endtest function
         (test nil) ; endtest form

@@ -1731,104 +1699,133 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
         (limit-constantp nil)
         (limit-value nil)
         )
         (limit-constantp nil)
         (limit-value nil)
         )

-     (when variable (loop-make-iteration-variable variable nil variable-type))
-     (do ((l prep-phrases (cdr l)) (prep) (form) (odir)) ((null l))
-       (setq prep (caar l) form (cadar l))
-       (case prep
-        ((:of :in)
-         (setq sequencep t)
-         (loop-make-variable sequence-variable form sequence-type))
-        ((:from :downfrom :upfrom)
-         (setq start-given t)
-         (cond ((eq prep :downfrom) (setq dir ':down))
-               ((eq prep :upfrom) (setq dir ':up)))
-         (multiple-value-setq (form start-constantp start-value)
-           (loop-constant-fold-if-possible form indexv-type))
-         (loop-make-iteration-variable indexv form indexv-type))
-        ((:upto :to :downto :above :below)
-         (cond ((loop-tequal prep :upto) (setq inclusive-iteration
-                                               (setq dir ':up)))
-               ((loop-tequal prep :to) (setq inclusive-iteration t))
-               ((loop-tequal prep :downto) (setq inclusive-iteration
-                                                 (setq dir ':down)))
-               ((loop-tequal prep :above) (setq dir ':down))
-               ((loop-tequal prep :below) (setq dir ':up)))
-         (setq limit-given t)
-         (multiple-value-setq (form limit-constantp limit-value)
-           (loop-constant-fold-if-possible form indexv-type))
-         (setq endform (if limit-constantp
-                           `',limit-value
-                           (loop-make-variable
-                             (loop-gentemp 'loop-limit-) form indexv-type))))
-        (:by
-          (multiple-value-setq (form stepby-constantp stepby)
-            (loop-constant-fold-if-possible form indexv-type))
-          (unless stepby-constantp
-            (loop-make-variable (setq stepby (loop-gentemp 'loop-step-by-))
-                                form
-                                indexv-type)))
-        (t (loop-error
-             "~S invalid preposition in sequencing or sequence path;~@
-              maybe invalid prepositions were specified in iteration path descriptor?"
-             prep)))
-       (when (and odir dir (not (eq dir odir)))
-        (loop-error "conflicting stepping directions in LOOP sequencing path"))
-       (setq odir dir))
-     (when (and sequence-variable (not sequencep))
-       (loop-error "missing OF or IN phrase in sequence path"))
-     ;; Now fill in the defaults.
-     (unless start-given
-       (loop-make-iteration-variable
-        indexv
-        (setq start-constantp t
-              start-value (or (loop-typed-init indexv-type) 0))
-        indexv-type))
-     (cond ((member dir '(nil :up))
-           (when (or limit-given default-top)
-             (unless limit-given
-               (loop-make-variable (setq endform
-                                         (loop-gentemp 'loop-seq-limit-))
-                                   nil indexv-type)
-               (push `(setq ,endform ,default-top) *loop-prologue*))
-             (setq testfn (if inclusive-iteration '> '>=)))
-           (setq step (if (eql stepby 1) `(1+ ,indexv) `(+ ,indexv ,stepby))))
-          (t (unless start-given
-               (unless default-top
-                 (loop-error "don't know where to start stepping"))
-               (push `(setq ,indexv (1- ,default-top)) *loop-prologue*))
-             (when (and default-top (not endform))
-               (setq endform (loop-typed-init indexv-type)
-                     inclusive-iteration t))
-             (when endform (setq testfn (if inclusive-iteration  '< '<=)))
-             (setq step
-                   (if (eql stepby 1) `(1- ,indexv) `(- ,indexv ,stepby)))))
-     (when testfn
-       (setq test
-            (hide-variable-reference t indexv `(,testfn ,indexv ,endform))))
-     (when step-hack
-       (setq step-hack
-            `(,variable ,(hide-variable-reference indexv-user-specified-p
-                                                  indexv
-                                                  step-hack))))
-     (let ((first-test test) (remaining-tests test))
-       (when (and stepby-constantp start-constantp limit-constantp)
-        (when (setq first-test
-                    (funcall (symbol-function testfn)
-                             start-value
-                             limit-value))
-          (setq remaining-tests t)))
-       `(() (,indexv ,(hide-variable-reference t indexv step))
-        ,remaining-tests ,step-hack () () ,first-test ,step-hack))))
+     (flet ((assert-index-for-arithmetic (index)
+             (unless (atom index)
+               (loop-error "Arithmetic index must be an atom."))))
+       (when variable (loop-make-iteration-var variable nil variable-type))
+       (do ((l prep-phrases (cdr l)) (prep) (form) (odir)) ((null l))
+        (setq prep (caar l) form (cadar l))
+        (case prep
+          ((:of :in)
+           (setq sequencep t)
+           (loop-make-var sequence-variable form sequence-type))
+          ((:from :downfrom :upfrom)
+           (setq start-given t)
+           (cond ((eq prep :downfrom) (setq dir ':down))
+                 ((eq prep :upfrom) (setq dir ':up)))
+           (multiple-value-setq (form start-constantp start-value)
+             (loop-constant-fold-if-possible form indexv-type))
+           (assert-index-for-arithmetic indexv)
+           ;; KLUDGE: loop-make-var generates a temporary symbol for
+           ;; indexv if it is NIL. We have to use it to have the index
+           ;; actually count
+           (setq indexv (loop-make-iteration-var indexv form indexv-type)))
+          ((:upto :to :downto :above :below)
+           (cond ((loop-tequal prep :upto) (setq inclusive-iteration
+                                                 (setq dir ':up)))
+                 ((loop-tequal prep :to) (setq inclusive-iteration t))
+                 ((loop-tequal prep :downto) (setq inclusive-iteration
+                                                   (setq dir ':down)))
+                 ((loop-tequal prep :above) (setq dir ':down))
+                 ((loop-tequal prep :below) (setq dir ':up)))
+           (setq limit-given t)
+           (multiple-value-setq (form limit-constantp limit-value)
+             (loop-constant-fold-if-possible form `(and ,indexv-type real)))
+           (setq endform (if limit-constantp
+                             `',limit-value
+                             (loop-make-var
+                                (gensym "LOOP-LIMIT-") form
+                                `(and ,indexv-type real)))))
+          (:by
+           (multiple-value-setq (form stepby-constantp stepby)
+             (loop-constant-fold-if-possible form `(and ,indexv-type (real (0)))))
+           (unless stepby-constantp
+             (loop-make-var (setq stepby (gensym "LOOP-STEP-BY-"))
+                form
+                `(and ,indexv-type (real (0)))
+                nil t)))
+          (t (loop-error
+                "~S invalid preposition in sequencing or sequence path;~@
+             maybe invalid prepositions were specified in iteration path descriptor?"
+                prep)))
+        (when (and odir dir (not (eq dir odir)))
+          (loop-error "conflicting stepping directions in LOOP sequencing path"))
+        (setq odir dir))
+       (when (and sequence-variable (not sequencep))
+        (loop-error "missing OF or IN phrase in sequence path"))
+       ;; Now fill in the defaults.
+       (if start-given
+          (when limit-given
+            ;; if both start and limit are given, they had better both
+            ;; be REAL.  We already enforce the REALness of LIMIT,
+            ;; above; here's the KLUDGE to enforce the type of START.
+            (flet ((type-declaration-of (x)
+                     (and (eq (car x) 'type) (caddr x))))
+              (let ((decl (find indexv *loop-declarations*
+                                :key #'type-declaration-of))
+                    (%decl (find indexv *loop-declarations*
+                                 :key #'type-declaration-of
+                                 :from-end t)))
+                (sb!int:aver (eq decl %decl))
+                (setf (cadr decl)
+                      `(and real ,(cadr decl))))))
+          ;; default start
+          ;; DUPLICATE KLUDGE: loop-make-var generates a temporary
+          ;; symbol for indexv if it is NIL. See also the comment in
+          ;; the (:from :downfrom :upfrom) case
+          (progn
+            (assert-index-for-arithmetic indexv)
+            (setq indexv
+                  (loop-make-iteration-var
+                     indexv
+                     (setq start-constantp t
+                           start-value (or (loop-typed-init indexv-type) 0))
+                     `(and ,indexv-type real)))))
+       (cond ((member dir '(nil :up))
+             (when (or limit-given default-top)
+               (unless limit-given
+                 (loop-make-var (setq endform (gensym "LOOP-SEQ-LIMIT-"))
+                    nil
+                    indexv-type)
+                 (push `(setq ,endform ,default-top) *loop-prologue*))
+               (setq testfn (if inclusive-iteration '> '>=)))
+             (setq step (if (eql stepby 1) `(1+ ,indexv) `(+ ,indexv ,stepby))))
+            (t (unless start-given
+                 (unless default-top
+                   (loop-error "don't know where to start stepping"))
+                 (push `(setq ,indexv (1- ,default-top)) *loop-prologue*))
+               (when (and default-top (not endform))
+                 (setq endform (loop-typed-init indexv-type)
+                       inclusive-iteration t))
+               (when endform (setq testfn (if inclusive-iteration  '< '<=)))
+               (setq step
+                     (if (eql stepby 1) `(1- ,indexv) `(- ,indexv ,stepby)))))
+       (when testfn
+        (setq test
+              `(,testfn ,indexv ,endform)))
+       (when step-hack
+        (setq step-hack
+              `(,variable ,step-hack)))
+       (let ((first-test test) (remaining-tests test))
+        (when (and stepby-constantp start-constantp limit-constantp
+                   (realp start-value) (realp limit-value))
+          (when (setq first-test
+                      (funcall (symbol-function testfn)
+                               start-value
+                               limit-value))
+            (setq remaining-tests t)))
+        `(() (,indexv ,step)
+          ,remaining-tests ,step-hack () () ,first-test ,step-hack)))))

 \f
 ;;;; interfaces to the master sequencer
 
 (defun loop-for-arithmetic (var val data-type kwd)
   (loop-sequencer
 \f
 ;;;; interfaces to the master sequencer
 
 (defun loop-for-arithmetic (var val data-type kwd)
   (loop-sequencer

-    var (loop-check-data-type data-type *loop-real-data-type*) t
-    nil nil nil nil nil nil
-    (loop-collect-prepositional-phrases
-      '((:from :upfrom :downfrom) (:to :upto :downto :above :below) (:by))
-      nil (list (list kwd val)))))
+   var (loop-check-data-type data-type 'number)
+   nil nil nil nil nil nil
+   (loop-collect-prepositional-phrases
+    '((:from :upfrom :downfrom) (:to :upto :downto :above :below) (:by))
+    nil (list (list kwd val)))))

 
 (defun loop-sequence-elements-path (variable data-type prep-phrases
                                    &key
 
 (defun loop-sequence-elements-path (variable data-type prep-phrases
                                    &key

@@ -1836,16 +1833,16 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
                                    size-function
                                    sequence-type
                                    element-type)
                                    size-function
                                    sequence-type
                                    element-type)

-  (multiple-value-bind (indexv indexv-user-specified-p) (named-variable 'index)
-    (let ((sequencev (named-variable 'sequence)))
+  (multiple-value-bind (indexv) (loop-named-var 'index)
+    (let ((sequencev (loop-named-var 'sequence)))

       (list* nil nil                           ; dummy bindings and prologue
             (loop-sequencer
       (list* nil nil                           ; dummy bindings and prologue
             (loop-sequencer

-              indexv 'fixnum indexv-user-specified-p
-              variable (or data-type element-type)
-              sequencev sequence-type
-              `(,fetch-function ,sequencev ,indexv)
-              `(,size-function ,sequencev)
-              prep-phrases)))))
+             indexv 'fixnum 
+             variable (or data-type element-type)
+             sequencev sequence-type
+             `(,fetch-function ,sequencev ,indexv)
+             `(,size-function ,sequencev)
+             prep-phrases)))))

 \f
 ;;;; builtin LOOP iteration paths
 
 \f
 ;;;; builtin LOOP iteration paths
 

@@ -1857,69 +1854,76 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
 ||#
 
 (defun loop-hash-table-iteration-path (variable data-type prep-phrases
 ||#
 
 (defun loop-hash-table-iteration-path (variable data-type prep-phrases

-                                      &key (which (required-argument)))
+                                      &key (which (sb!int:missing-arg)))

   (declare (type (member :hash-key :hash-value) which))
   (cond ((or (cdr prep-phrases) (not (member (caar prep-phrases) '(:in :of))))
         (loop-error "too many prepositions!"))
        ((null prep-phrases)
         (loop-error "missing OF or IN in ~S iteration path")))
   (declare (type (member :hash-key :hash-value) which))
   (cond ((or (cdr prep-phrases) (not (member (caar prep-phrases) '(:in :of))))
         (loop-error "too many prepositions!"))
        ((null prep-phrases)
         (loop-error "missing OF or IN in ~S iteration path")))

-  (let ((ht-var (loop-gentemp 'loop-hashtab-))
-       (next-fn (loop-gentemp 'loop-hashtab-next-))
+  (let ((ht-var (gensym "LOOP-HASHTAB-"))
+       (next-fn (gensym "LOOP-HASHTAB-NEXT-"))

        (dummy-predicate-var nil)
        (post-steps nil))
     (multiple-value-bind (other-var other-p)
        (dummy-predicate-var nil)
        (post-steps nil))
     (multiple-value-bind (other-var other-p)

-       (named-variable (if (eq which 'hash-key) 'hash-value 'hash-key))
-      ;; @@@@ named-variable returns a second value of T if the name was
-      ;; actually specified, so clever code can throw away the gensym'ed up
-      ;; variable if it isn't really needed. The following is for those
-      ;; implementations in which we cannot put dummy NILs into
-      ;; multiple-value-setq variable lists.
+       (loop-named-var (ecase which
+                         (:hash-key 'hash-value)
+                         (:hash-value 'hash-key)))
+      ;; @@@@ LOOP-NAMED-VAR returns a second value of T if the name
+      ;; was actually specified, so clever code can throw away the
+      ;; GENSYM'ed-up variable if it isn't really needed. The
+      ;; following is for those implementations in which we cannot put
+      ;; dummy NILs into MULTIPLE-VALUE-SETQ variable lists.

       (setq other-p t
       (setq other-p t

-           dummy-predicate-var (loop-when-it-variable))
-      (let ((key-var nil)
-           (val-var nil)
-           (bindings `((,variable nil ,data-type)
-                       (,ht-var ,(cadar prep-phrases))
-                       ,@(and other-p other-var `((,other-var nil))))))
-       (if (eq which 'hash-key)
-           (setq key-var variable val-var (and other-p other-var))
-           (setq key-var (and other-p other-var) val-var variable))
+           dummy-predicate-var (loop-when-it-var))
+      (let* ((key-var nil)
+            (val-var nil)
+            (variable (or variable (gensym "LOOP-HASH-VAR-TEMP-")))
+            (bindings `((,variable nil ,data-type)
+                        (,ht-var ,(cadar prep-phrases))
+                        ,@(and other-p other-var `((,other-var nil))))))
+       (ecase which
+         (:hash-key (setq key-var variable
+                          val-var (and other-p other-var)))
+         (:hash-value (setq key-var (and other-p other-var)
+                            val-var variable)))

        (push `(with-hash-table-iterator (,next-fn ,ht-var)) *loop-wrappers*)
        (push `(with-hash-table-iterator (,next-fn ,ht-var)) *loop-wrappers*)

-       (when (consp key-var)
-         (setq post-steps
-               `(,key-var ,(setq key-var (loop-gentemp 'loop-hash-key-temp-))
-                          ,@post-steps))
-         (push `(,key-var nil) bindings))
-       (when (consp val-var)
-         (setq post-steps
-               `(,val-var ,(setq val-var (loop-gentemp 'loop-hash-val-temp-))
-                          ,@post-steps))
-         (push `(,val-var nil) bindings))
-       `(,bindings                             ;bindings
-         ()                                    ;prologue
-         ()                                    ;pre-test
-         ()                                    ;parallel steps
+        (when (or (consp key-var) data-type)
+          (setq post-steps
+                `(,key-var ,(setq key-var (gensym "LOOP-HASH-KEY-TEMP-"))
+                           ,@post-steps))
+          (push `(,key-var nil) bindings))
+        (when (or (consp val-var) data-type)
+          (setq post-steps
+                `(,val-var ,(setq val-var (gensym "LOOP-HASH-VAL-TEMP-"))
+                           ,@post-steps))
+          (push `(,val-var nil) bindings))
+       `(,bindings                     ;bindings
+         ()                            ;prologue
+         ()                            ;pre-test
+         ()                            ;parallel steps

          (not (multiple-value-setq (,dummy-predicate-var ,key-var ,val-var)
          (not (multiple-value-setq (,dummy-predicate-var ,key-var ,val-var)

-                (,next-fn)))   ;post-test
+                (,next-fn)))           ;post-test

          ,post-steps)))))
 
 (defun loop-package-symbols-iteration-path (variable data-type prep-phrases
                                            &key symbol-types)
          ,post-steps)))))
 
 (defun loop-package-symbols-iteration-path (variable data-type prep-phrases
                                            &key symbol-types)

-  (cond ((or (cdr prep-phrases) (not (member (caar prep-phrases) '(:in :of))))
+  (cond ((and prep-phrases (cdr prep-phrases))

         (loop-error "Too many prepositions!"))
         (loop-error "Too many prepositions!"))

-       ((null prep-phrases)
-        (loop-error "missing OF or IN in ~S iteration path")))
+        ((and prep-phrases (not (member (caar prep-phrases) '(:in :of))))
+         (sb!int:bug "Unknown preposition ~S." (caar prep-phrases))))

   (unless (symbolp variable)
     (loop-error "Destructuring is not valid for package symbol iteration."))
   (unless (symbolp variable)
     (loop-error "Destructuring is not valid for package symbol iteration."))

-  (let ((pkg-var (loop-gentemp 'loop-pkgsym-))
-       (next-fn (loop-gentemp 'loop-pkgsym-next-)))
+  (let ((pkg-var (gensym "LOOP-PKGSYM-"))
+       (next-fn (gensym "LOOP-PKGSYM-NEXT-"))
+       (variable (or variable (gensym "LOOP-PKGSYM-VAR-")))
+        (package (or (cadar prep-phrases) '*package*)))

     (push `(with-package-iterator (,next-fn ,pkg-var ,@symbol-types))
          *loop-wrappers*)
     (push `(with-package-iterator (,next-fn ,pkg-var ,@symbol-types))
          *loop-wrappers*)

-    `(((,variable nil ,data-type) (,pkg-var ,(cadar prep-phrases)))
+    `(((,variable nil ,data-type) (,pkg-var ,package))

       ()
       ()
       ()
       ()
       ()
       ()

-      (not (multiple-value-setq (,(loop-when-it-variable)
+      (not (multiple-value-setq (,(loop-when-it-var)

                                 ,variable)
             (,next-fn)))
       ())))
                                 ,variable)
             (,next-fn)))
       ())))

@@ -1928,7 +1932,7 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
 
 (defun make-ansi-loop-universe (extended-p)
   (let ((w (make-standard-loop-universe
 
 (defun make-ansi-loop-universe (extended-p)
   (let ((w (make-standard-loop-universe

-            :keywords `((named (loop-do-named))
+            :keywords '((named (loop-do-named))

                         (initially (loop-do-initially))
                         (finally (loop-do-finally))
                         (do (loop-do-do))
                         (initially (loop-do-initially))
                         (finally (loop-do-finally))
                         (do (loop-do-do))

@@ -1941,10 +1945,10 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
                         (nconc (loop-list-collection nconc))
                         (nconcing (loop-list-collection nconc))
                         (count (loop-sum-collection count
                         (nconc (loop-list-collection nconc))
                         (nconcing (loop-list-collection nconc))
                         (count (loop-sum-collection count

-                                                    ,*loop-real-data-type*
+                                                    real

                                                     fixnum))
                         (counting (loop-sum-collection count
                                                     fixnum))
                         (counting (loop-sum-collection count

-                                                       ,*loop-real-data-type*
+                                                       real

                                                        fixnum))
                         (sum (loop-sum-collection sum number number))
                         (summing (loop-sum-collection sum number number))
                                                        fixnum))
                         (sum (loop-sum-collection sum number number))
                         (summing (loop-sum-collection sum number number))

@@ -1960,7 +1964,8 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
                         (when (loop-do-if when nil))   ; Normal, do when
                         (if (loop-do-if if nil))       ; synonymous
                         (unless (loop-do-if unless t)) ; Negate test on when
                         (when (loop-do-if when nil))   ; Normal, do when
                         (if (loop-do-if if nil))       ; synonymous
                         (unless (loop-do-if unless t)) ; Negate test on when

-                        (with (loop-do-with)))
+                        (with (loop-do-with))
+                         (repeat (loop-do-repeat)))

             :for-keywords '((= (loop-ansi-for-equals))
                             (across (loop-for-across))
                             (in (loop-for-in))
             :for-keywords '((= (loop-ansi-for-equals))
                             (across (loop-for-across))
                             (in (loop-for-in))

@@ -1969,12 +1974,14 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
                             (downfrom (loop-for-arithmetic :downfrom))
                             (upfrom (loop-for-arithmetic :upfrom))
                             (below (loop-for-arithmetic :below))
                             (downfrom (loop-for-arithmetic :downfrom))
                             (upfrom (loop-for-arithmetic :upfrom))
                             (below (loop-for-arithmetic :below))

+                             (above (loop-for-arithmetic :above))

                             (to (loop-for-arithmetic :to))
                             (upto (loop-for-arithmetic :upto))
                             (to (loop-for-arithmetic :to))
                             (upto (loop-for-arithmetic :upto))

+                            (downto (loop-for-arithmetic :downto))
+                            (by (loop-for-arithmetic :by))

                             (being (loop-for-being)))
             :iteration-keywords '((for (loop-do-for))
                             (being (loop-for-being)))
             :iteration-keywords '((for (loop-do-for))

-                                  (as (loop-do-for))
-                                  (repeat (loop-do-repeat)))
+                                  (as (loop-do-for)))

             :type-symbols '(array atom bignum bit bit-vector character
                             compiled-function complex cons double-float
                             fixnum float function hash-table integer
             :type-symbols '(array atom bignum bit bit-vector character
                             compiled-function complex cons double-float
                             fixnum float function hash-table integer

@@ -2009,7 +2016,8 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
                   'loop-package-symbols-iteration-path w
                   :preposition-groups '((:of :in))
                   :inclusive-permitted nil
                   'loop-package-symbols-iteration-path w
                   :preposition-groups '((:of :in))
                   :inclusive-permitted nil

-                  :user-data '(:symbol-types (:internal)))
+                  :user-data '(:symbol-types (:internal
+                                              :external)))

     w))
 
 (defparameter *loop-ansi-universe*
     w))
 
 (defparameter *loop-ansi-universe*

@@ -2017,9 +2025,9 @@ a LET-like macro, and a SETQ-like macro, which perform LOOP-style destructuring.
 
 (defun loop-standard-expansion (keywords-and-forms environment universe)
   (if (and keywords-and-forms (symbolp (car keywords-and-forms)))
 
 (defun loop-standard-expansion (keywords-and-forms environment universe)
   (if (and keywords-and-forms (symbolp (car keywords-and-forms)))

-    (loop-translate keywords-and-forms environment universe)
-    (let ((tag (gensym)))
-      `(block nil (tagbody ,tag (progn ,@keywords-and-forms) (go ,tag))))))
+      (loop-translate keywords-and-forms environment universe)
+      (let ((tag (gensym)))
+       `(block nil (tagbody ,tag (progn ,@keywords-and-forms) (go ,tag))))))

 
 (sb!int:defmacro-mundanely loop (&environment env &rest keywords-and-forms)
   (loop-standard-expansion keywords-and-forms env *loop-ansi-universe*))
 
 (sb!int:defmacro-mundanely loop (&environment env &rest keywords-and-forms)
   (loop-standard-expansion keywords-and-forms env *loop-ansi-universe*))