Small fixes & updates.

scsh/lib/list-lib.scm

@@ -79,18 +79,34 @@
 ;;; This is carefully tuned code; do not modify casually.
 ;;;   - It is careful to share storage when possible;
 ;;;   - Side-effecting code tries not to perform redundant writes.
+;;; 
 ;;; That said, a port of this library to a specific Scheme system might wish
-;;; to tune this code to exploit particulars of the implementation. In
+;;; to tune this code to exploit particulars of the implementation. 
-;;; particular, the n-ary mapping functions are particularly slow and
+;;; The single most important compiler-specific optimisation you could make
-;;; cons-intensive, and are good candidates for tuning. I have coded fast
+;;; to this library would be to add rewrite rules or transforms to:
-;;; paths for the single-list cases, but what you really want to do is exploit
+;;; - transform applications of n-ary procedures (e.g. LIST=, CONS*, APPEND,
-;;; the fact that the compiler usually knows how many arguments are being 
+;;;   LSET-UNION) into multiple applications of a primitive two-argument 
-;;; passed to a particular application of these functions -- they are usually
+;;;   variant.
-;;; explicitly called, not passed around as higher-order values. If you can 
+;;; - transform applications of the mapping functions (MAP, FOR-EACH, FOLD, 
-;;; arrange to have your compiler produce custom code or custom linkages based
+;;;   ANY, EVERY) into open-coded loops. The killer here is that these 
-;;; on the number of arguments in the call, you can speed these functions up 
+;;;   functions are n-ary. Handling the general case is quite inefficient,
-;;; a *lot*. But this kind of compiler technology no longer exists in the 
+;;;   requiring many intermediate data structures to be allocated and
-;;; Scheme world as far as I can see.
+;;;   discarded.
+;;; - transform applications of procedures that take optional arguments
+;;;   into calls to variants that do not take optional arguments. This
+;;;   eliminates unnecessary consing and parsing of the rest parameter.
+;;;
+;;; These transforms would provide BIG speedups. In particular, the n-ary
+;;; mapping functions are particularly slow and cons-intensive, and are good
+;;; candidates for tuning. I have coded fast paths for the single-list cases,
+;;; but what you really want to do is exploit the fact that the compiler
+;;; usually knows how many arguments are being passed to a particular
+;;; application of these functions -- they are usually explicitly called, not
+;;; passed around as higher-order values. If you can arrange to have your
+;;; compiler produce custom code or custom linkages based on the number of
+;;; arguments in the call, you can speed these functions up a *lot*. But this
+;;; kind of compiler technology no longer exists in the Scheme world as far as
+;;; I can see.
 ;;;
 ;;; Note that this code is, of course, dependent upon standard bindings for
 ;;; the R5RS procedures -- i.e., it assumes that the variable CAR is bound
@@ -1192,23 +1208,25 @@
 ;;; linear-time algorithm to kill the dups. Or use an algorithm based on
 ;;; element-marking. The former gives you O(n lg n), the latter is linear.
 
-(define (delete-duplicates elt= lis)
+(define (delete-duplicates lis . maybe-=)
-  (check-arg procedure? elt= delete-duplicates)
+  (let ((elt= (:optional maybe-= equal?)))
-  (let recur ((lis lis))
+    (check-arg procedure? elt= delete-duplicates)
-    (if (null-list? lis) lis
+    (let recur ((lis lis))
-	(let* ((x (car lis))
+      (if (null-list? lis) lis
-	       (tail (cdr lis))
+	  (let* ((x (car lis))
-	       (new-tail (recur (delete x tail elt=))))
+		 (tail (cdr lis))
-	  (if (eq? tail new-tail) lis (cons x new-tail))))))
+		 (new-tail (recur (delete x tail elt=))))
+	    (if (eq? tail new-tail) lis (cons x new-tail)))))))
 
-(define (delete-duplicates! elt= lis)
+(define (delete-duplicates! lis maybe-=)
-  (check-arg procedure? elt= delete-duplicates!)
+  (let ((elt= (:optional maybe-= equal?)))
-  (let recur ((lis lis))
+    (check-arg procedure? elt= delete-duplicates!)
-    (if (null-list? lis) lis
+    (let recur ((lis lis))
-	(let* ((x (car lis))
+      (if (null-list? lis) lis
-	       (tail (cdr lis))
+	  (let* ((x (car lis))
-	       (new-tail (recur (delete! x tail elt=))))
+		 (tail (cdr lis))
-	  (if (eq? tail new-tail) lis (cons x new-tail))))))
+		 (new-tail (recur (delete! x tail elt=))))
+	    (if (eq? tail new-tail) lis (cons x new-tail)))))))
 
 
 ;;; alist stuff
@@ -1382,7 +1400,7 @@
 		  ((null? ans) lis) 	; if we don't have to.
 		  ((eq? lis ans) ans)
 		  (else
-		   (fold (lambda (elt ans) (if (any (lambda (x) (= x elt)))
+		   (fold (lambda (elt ans) (if (any (lambda (x) (= x elt)) ans)
 					       ans
 					       (cons elt ans)))
 			 ans lis))))

scsh/lib/list-pack.scm

@@ -60,7 +60,7 @@
    ;; list-copy lis
    (list-copy (proc (:value) :value))
 
-   (circular-list (proc (:value &opt :value) :pair))
+   (circular-list (proc (:value &rest :value) :pair))
 
 ;  ((:iota iota:)
 ;   (proc (:number &opt :number :number) :value))
@@ -102,7 +102,7 @@
    (unzip4 (proc (:value) (some-values :value :value :value :value)))
    (unzip5 (proc (:value) (some-values :value :value :value :value :value)))
 
-   (count (proc ((proc (:value) :boolean) :value) :exact-integer))
+   (count (proc ((proc (:value &rest :value) :boolean) :value) :exact-integer))
 
    ((fold fold-right)
     (proc ((proc (:value :value &rest :value) :value)

scsh/lib/srfi-1.html

@@ -1,8 +1,7 @@
 <!doctype html public '-//W3C//DTD HTML 4.0//EN'
   'http://www.w3.org/TR/REC-html40/strict.dtd'>
 
-<!-- insert p tags
+<!-- Is there a portable way to write an em-dash?
-     Is there a portable way to write an em-dash?
      Can I have bangs, plusses, or slashes in #tags? Spaces?
 	Yes: plus, bang, star   No: space  Yes: slash, question, ampersand
 	You can't put sharp in a path, so anything goes, really.
@@ -86,7 +85,7 @@
 	   /* R5RS proc names are in italic; extended R5RS names 
            ** in italic boldface.
 	   */
-	   span.r5rs-proc { font-style: italic; }
+	   span.r5rs-proc { font-weight: bold; }
 	   span.r5rs-procx { font-style: italic; font-weight: bold; }
 
 	   /* Spread out bibliographic lists. */
@@ -111,9 +110,13 @@
 	   ** here. Perhaps, one day, when these rendering bugs are fixed,
 	   ** this gross hackery can be removed.
 	   */
-	   dt.proc-def1 { margin-top: 2ex; margin-bottom: 0ex; }
+	   dt.proc-def1 { margin-top: 3ex; margin-bottom: 0ex; }
 	   dt.proc-defi { margin-top: 0ex; margin-bottom: 0ex; }
 	   dt.proc-defn { margin-top: 0ex; margin-bottom: 0.5ex; }
+	   dt.proc-def  { margin-top: 3ex; margin-bottom: 0.5ex; }
+
+	   pre { margin-top: 1ex; }
+
 	   dd.proc-def { margin-bottom: 2ex; margin-top: 0.5ex; } 
 
 	   /* For the index of procedures. 
@@ -123,7 +126,7 @@
 	   pre.proc-index { margin-top: 0ex; }
 
 	   /* Spread out bibliographic lists. */
-	   dt.biblio { margin-bottom: 0ex; }
+	   dt.biblio { margin-top: 3ex; margin-bottom: 0ex; }
 	   dd.biblio { margin-bottom: 1ex; }
     </style>
   </head>
@@ -218,7 +221,7 @@ of the other big, full-featured Schemes. The complete list of list-processing
 systems I checked is:
 <div class=indent>
     <abbr title="Revised^4 Report on Scheme">R4RS</abbr>/<abbr title="Revised^5 Report on Scheme"><a href="#R5RS">R5RS</a></abbr> Scheme, MIT Scheme, Gambit, RScheme, MzScheme, slib, 
-    <a href="#CLtL2">Common Lisp</a>, Bigloo, guile, T, APL and the SML standard basis
+    <a href="#CommonLisp">Common Lisp</a>, Bigloo, guile, T, APL and the SML standard basis
 </div>
 <p>
 As a result, the library I am proposing is fairly rich.
@@ -250,8 +253,7 @@ implementation. I have placed this source on the Net with an unencumbered,
         </ul>
 
 <li>It is written for clarity and well-commented. The current source is
-    1436 lines of text, of which 690 are source code; the rest being comments
+    706 lines of source code and 818 lines of comments and white space.
-    and blank lines.
 
 <li>It is written for efficiency. Fast paths are provided for common
     cases. Side-effecting procedures such as <code>filter!</code> avoid unnecessary,
@@ -277,7 +279,7 @@ library and get good results with it.
 <p>
 Here is a short list of the procedures provided by the list-lib package.
 <a href="#R5RS">R5RS</a></abbr> procedures are shown in 
-<span class=r5rs-proc>italic</span class=r5rs-proc>;
+<span class=r5rs-proc>bold</span class=r5rs-proc>;
 extended <a href="#R5RS">R5RS</a></abbr> 
          procedures, in <span class=r5rs-procx>bold italic</span>.
 <div class=indent>
@@ -658,7 +660,7 @@ The following items are not in this library:
 <li>Tree-processing routines
 </ul>
 <p>
-They shound have their own <abbr title="Scheme Request for Implementation">SRFI</abbr> specs.
+They should have their own <abbr title="Scheme Request for Implementation">SRFI</abbr> specs.
 <p>
 
 
@@ -688,16 +690,15 @@ The templates given below obey the following conventions for procedure formals:
     <td> A natural number (an integer &gt;= 0)
 <tr valign=baseline><th align=left> <var>proc</var>
     <td> A procedure
+<tr valign=baseline><th align=left> <var>pred</var>
+    <td> A procedure whose return value is treated as a boolean
 <tr valign=baseline><th align=left> <var>=</var>
     <td> A boolean procedure taking two arguments
-<tr valign=baseline><th align=left> <var>pred</var>
-    <td> A boolean procedure taking one argument
 </table>
 
 <p>
 It is an error to pass a circular or dotted list to a procedure not
-defined to accept such an argument. Such a procedure may either signal
+defined to accept such an argument.
-an error or diverge when passed a circular list.
 
 <!--========================================================================-->
 <h2><a name="Constructors">Constructors</a></h2>
@@ -771,7 +772,7 @@ an error or diverge when passed a circular list.
     <div class=indent><code>
 (cons <var>elt<sub>1</sub></var> (cons <var>elt<sub>2</sub></var> (cons ... <var>elt<sub>n</sub></var>)))
     </code></div>
-    This function is called <code>list*</code> in <a href="#CLtL2">Common Lisp</a> and about 
+    This function is called <code>list*</code> in <a href="#CommonLisp">Common Lisp</a> and about 
     half of the Schemes that provide it,
     and <code>cons*</code> in the other half.
 <pre class=code-example>
@@ -783,7 +784,7 @@ an error or diverge when passed a circular list.
 ==== make-list
 ============================================================================-->
 <a name="make-list"></a>
-<dt class=proc-def> <code class=proc-def>make-list <var>n [fill] -&gt; list</var></code>
+<dt class=proc-def> <code class=proc-def>make-list</code> <var>n [fill] -&gt; list</var>
 <dd class=proc-def>
     Returns an <var>n</var>-element list, 
     whose elements are all the value <var>fill</var>.
@@ -870,7 +871,7 @@ partition the entire universe of Scheme values.
     Note that this definition rules out circular lists. This
     function is required to detect this case and return false.
 <p>
-    Nil-terminated lists are called "proper" lists by <abbr title="Revised^5 Report on Scheme"><a href="#R5RS">R5RS</a></abbr> and <a href="#CLtL2">Common Lisp</a>.
+    Nil-terminated lists are called "proper" lists by <abbr title="Revised^5 Report on Scheme"><a href="#R5RS">R5RS</a></abbr> and <a href="#CommonLisp">Common Lisp</a>.
     The opposite of proper is improper.
 <p>
     <abbr title="Revised^5 Report on Scheme"><a href="#R5RS">R5RS</a></abbr> binds this function to the variable <code>list?</code>.
@@ -1011,7 +1012,8 @@ partition the entire universe of Scheme values.
         <code>(eq? <var>x</var> <var>y</var>)</code> => <code>(<var>elt=</var> <var>x</var> <var>y</var>)</code>.
 </div>
     Note that this implies that two lists which are <code>eq?</code> 
-    are always <var>list=</var>, as well.
+    are always <var>list=</var>, as well; implementations may exploit this
+    fact to "short-cut" the element-by-element comparisons.
 <pre class=code-example>
 (list= eq?) => #t       ; Trivial cases
 (list= eq? '(a)) => #t
@@ -1318,6 +1320,8 @@ partition the entire universe of Scheme values.
 <pre class=code-example>
 (append '(a b) '(c . d))  =>  (a b c . d)
 (append '() 'a)           =>  a
+(append '(x y))           =>  (x y)
+(append)                  =>  ()
 </pre>
 
     <code>append!</code> is the "linear-update" variant of <code>append</code>
@@ -1565,7 +1569,8 @@ partition the entire universe of Scheme values.
                               (pair-fold <var>kons</var> (<var>kons</var> <var>lis</var> <var>knil</var>) tail))
 (pair-fold <var>kons</var> <var>knil</var> <code>'()</code>) = <var>knil</var>
 </pre>
-    The <var>kons</var> function may reliably apply <code>set-cdr!</code> to the pairs it is given
+    For finite lists, the <var>kons</var> function may reliably apply
+    <code>set-cdr!</code> to the pairs it is given
     without altering the sequence of execution.
 <p>
     Example:
@@ -1754,10 +1759,10 @@ Otherwise,    return <code>(fold <var>f</var> (car <var>list</var>) (cdr <var>li
 
 <pre class=code-example>
 ;; List of squares: 1^2 ... 10^2
-(unfold (lambda (x) (&gt; x 10))
+(unfold-right (lambda (x) (&gt; x 10))
-        (lambda (x) (* x x))
+              (lambda (x) (* x x))
-	(lambda (x) (+ x 1))
+	      (lambda (x) (+ x 1))
-	1)
+	      1)
 		
 (unfold-right null-list? car cdr lis) ; Copy a proper list.
 
@@ -1870,10 +1875,7 @@ Otherwise,    return <code>(fold <var>f</var> (car <var>list</var>) (cdr <var>li
     specification to allow the arguments to be of unequal length; 
     it terminates when the shortest list runs out. 
 <p>
-    At least one of the argument lists must be finite:
+    At least one of the argument lists must be finite.
-<pre class=code-example>
-(map + '(3 1 4 1) (circular-list 1 0)) => (4 1 5 1)
-</pre>
 
 <!--
 ==== append-map!
@@ -2110,7 +2112,7 @@ these procedures work when applied to different kinds of lists:
                   satisfying the search criteria.
 </dl>
 <p>
-Here are some examples, using the <code>find</code> and <code>any</code> procedures as a canonical
+Here are some examples, using the <code>find</code> and <code>any</code> procedures as canonical
 representatives:
 <pre class=code-example>
 ;; Proper list -- success
@@ -2950,8 +2952,8 @@ assistance.
 <p>
 I am also grateful the authors, implementors and documentors of all the systems
 mentioned in the introduction. Aubrey Jaffer and Kent Pitman should be noted
-for their work in producing Web-accessible versions of the R5RS and Common
+for their work in producing Web-accessible versions of the R5RS and 
-Lisp spec, which was a tremendous aid.
+<a href="#CommonLisp">Common Lisp</a> spec, which was a tremendous aid.
 <p>
 This is not to imply that these individuals necessarily endorse the final
 results, of course. 
@@ -2998,11 +3000,17 @@ results, of course.
 <p>
 
 <dl>
-<dt class=biblio><strong><a name="CLtL2">[CLtL2]</a></strong></dt>
+<dt class=biblio><strong><a name="CommonLisp">[CommonLisp]</a></strong></dt>
 <dd><em>Common Lisp: the Language</em><br>
 Guy L. Steele Jr. (editor).<br>
 Digital Press, Maynard, Mass., second edition 1990.<br>
-Available at <a href="http://www.harlequin.com/education/books/HyperSpec/">
+Available at <a href="http://www.elwood.com/alu/table/references.htm#cltl2">
+http://www.elwood.com/alu/table/references.htm#cltl2</a>.
+<p>
+
+The Common Lisp "HyperSpec," produced by Kent Pitman, is essentially
+the ANSI spec for Common Lisp:
+<a href="http://www.harlequin.com/education/books/HyperSpec/">
 http://www.harlequin.com/education/books/HyperSpec/</a>.
 
 <dt class=biblio><strong><a name="R5RS">[R5RS]</a></strong></dt>

scsh/lib/srfi-1.txt

@@ -1,13 +1,9 @@
 The SRFI-1 list library						-*- outline -*-
 Olin Shivers
 98/10/16
-Last Update: 99/9/11
+Last Update: 99/10/2
 
-Todo: carefully proofread.
+Emacs should display this document in outline mode. Say c-h m for
-      Netscape prints with insufficient space between proc specs --
-          see list=, for example. Mess about with css some more.
-
-Emacs should display this document is in outline mode. Say c-h m for
 instructions on how to move through it by sections (e.g., c-c c-n, c-c c-p).
 During the SRFI discussion period, the current draft may be found at
     ftp://ftp.ai.mit.edu/people/shivers/srfi/srfi-1/srfi-1.txt
@@ -97,8 +93,7 @@ implementation. I have placed this source on the Net with an unencumbered,
 	- Use of a simple CHECK-ARG procedure for argument checking.
 
   - It is written for clarity and well-commented. The current source is
-    1436 lines of text, of which 690 are source code; the rest being comments
+    706 lines of source code and 818 lines of comments and white space.
-    and blank lines.
 
   - It is written for efficiency. Fast paths are provided for common
     cases. Side-effecting procedures such as FILTER! avoid unnecessary,
@@ -424,7 +419,7 @@ The following items are not in this library:
 - Sort routines
 - Destructuring/pattern-matching macro
 - Tree-processing routines
-They shound have their own SRFI specs.
+They should have their own SRFI specs.
 
 
 
@@ -442,12 +437,11 @@ The templates given below obey the following conventions for procedure formals:
     object, value	Any value
     n, i		A natural number (an integer >= 0)
     proc		A procedure
+    pred		A procedure whose return value is treated as a boolean
     =			A boolean procedure taking two arguments
-    pred		A boolean procedure taking one argument
 
 It is an error to pass a circular or dotted list to a procedure not
-defined to accept such an argument. Such a procedure may either signal
+defined to accept such an argument.
-an error or diverge when passed a circular list.
 
 ** Constructors
 ===============
@@ -614,7 +608,8 @@ list= elt= list1 ... -> boolean
     it must be the case that
 	(eq? x y) => (elt= x y).
     Note that this implies that two lists which are EQ? are always LIST=,
-    as well.
+    as well; implementations may exploit this fact to "short-cut" the
+    element-by-element comparisons.
 
     (list= eq?) => #t		; Trivial cases
     (list= eq? '(a)) => #t
@@ -776,6 +771,8 @@ append! list1 ... -> value
     
     (append '(a b) '(c . d))               ==>  (a b c . d)
     (append '() 'a)                        ==>  a
+    (append '(x y))                        ==>  (x y)
+    (append)                               ==>  ()
 
     APPEND! is the "linear-update" variant of APPEND -- it is allowed, but
     not required, to alter cons cells in the argument lists to construct
@@ -932,8 +929,8 @@ pair-fold kons knil clist1 clist2 ... -> value
 
 	(pair-fold kons knil '()) = knil
 
-    The KONS function may reliably apply SET-CDR! to the pairs it is given
+    For finite lists, the KONS function may reliably apply SET-CDR! to the
-    without altering the sequence of execution.
+    pairs it is given without altering the sequence of execution.
 
     Example:
       ;;; Destructively reverse a list.
@@ -1130,8 +1127,7 @@ for-each proc clist1 clist2 ... -> unspecified				R5RS+
     to allow the arguments to be of unequal length; it terminates
     when the shortest list runs out. 
 
-    At least one of the argument lists must be finite:
+    At least one of the argument lists must be finite.
-	(map + '(3 1 4 1) (circular-list 1 0)) => (4 1 5 1)
 
 append-map  f clist1 clist2 ... -> value
 append-map! f clist1 clist2 ... -> value
@@ -1279,7 +1275,7 @@ these procedures work when applied to different kinds of lists:
                   successful* -- that is, if the list contains an element
                   satisfying the search criteria.
 		  
-Here are some examples, using the FIND and ANY procedures as a canonical
+Here are some examples, using the FIND and ANY procedures as canonical
 representatives:
     ;; Proper list -- success
     (find even? '(1 2 3))	=> 2
@@ -1843,11 +1839,15 @@ SRFI web site:
     http://srfi.schemers.org/
 
 
-[CLtL2]
+[CommonLisp]
     Common Lisp: the Language
     Guy L. Steele Jr. (editor).
     Digital Press, Maynard, Mass., second edition 1990.
-    Available at http://www.harlequin.com/education/books/HyperSpec/
+    Available at http://www.elwood.com/alu/table/references.htm#cltl2
+
+    The Common Lisp "HyperSpec," produced by Kent Pitman, is essentially
+    the ANSI spec for Common Lisp:
+    http://www.harlequin.com/education/books/HyperSpec/
 
 [R5RS]
     Revised^5 Report on the Algorithmic Language Scheme, 
@@ -1905,8 +1905,9 @@ Ispell dumps "buffer local" words here. Please ignore.
  LocalWords:  arg LISTi pred cond LISTn ANY's EVERY's Uniquifying lg ridentity
  LocalWords:  eq netnews generalise Maciej Stachowiak al Bewig LocalWords ELTi
  LocalWords:  anamorphism apomorphism CLISTi ALIST's url ceteris eltn caar KNULL
- LocalWords:  deconstructor RIGHT's KAR KDR kar kdr knull HTML CLtL Clinger
+ LocalWords:  deconstructor RIGHT's KAR KDR kar kdr knull HTML CLtL Clinger gen
- LocalWords:  Rees Bawden Blandy Bornstein Bothner Carrico Currie Dybvig
+ LocalWords:  Rees Bawden Blandy Bornstein Bothner Carrico Currie Dybvig expt
- LocalWords:  Egorov Feeley Matthias Felleisen Flatt Hilsdale Hukriede
+ LocalWords:  Egorov Feeley Matthias Felleisen Flatt Hilsdale Hukriede CLISTs
- LocalWords:  Kolbly Shriram Krishnamurthi Jussi Piitulainen Pokorny Joerg
+ LocalWords:  Kolbly Shriram Krishnamurthi Jussi Piitulainen Pokorny Joerg Todo
- LocalWords:  Sperber Wittenberger documentors Jaffer
+ LocalWords:  Sperber Wittenberger documentors Jaffer initialised consed IE
+ LocalWords:  disarranging SIGPLAN CommonLisp cltl HyperSpec