Remove (ice-9 hcons)

It was never documented, never used, and uses the gross assoc interface
to doubly-weak tables.  Good-bye!

* module/ice-9/hcons.scm: Remove.
* am/bootstrap.am: Remove hcons from build.
* module/ice-9/poe.scm: Extract the one procedure from hcons that poe
uses, which notably doesn't have anything to do with hcons.

am/bootstrap.am

@@ -150,7 +150,6 @@ SOURCES =					\
   ice-9/getopt-long.scm				\
   ice-9/guardians.scm				\
   ice-9/hash-table.scm				\
-  ice-9/hcons.scm				\
   ice-9/history.scm				\
   ice-9/i18n.scm				\
   ice-9/iconv.scm				\

module/ice-9/hcons.scm

@@ -1,81 +0,0 @@
-;;; installed-scm-file
-
-;;;; 	Copyright (C) 1995, 1996, 1998, 2001, 2003, 2006, 2025 Free Software Foundation, Inc.
-;;;; 
-;;;; This library is free software; you can redistribute it and/or
-;;;; modify it under the terms of the GNU Lesser General Public
-;;;; License as published by the Free Software Foundation; either
-;;;; version 3 of the License, or (at your option) any later version.
-;;;; 
-;;;; This library is distributed in the hope that it will be useful,
-;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
-;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-;;;; Lesser General Public License for more details.
-;;;; 
-;;;; You should have received a copy of the GNU Lesser General Public
-;;;; License along with this library; if not, write to the Free Software
-;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
-;;;; 
-
-
-(define-module  (ice-9 hcons)
-  #:use-module (ice-9 weak-tables)
-  #:export (hashq-cons-hash hashq-cons-assoc hashq-cons-get-handle
-	    hashq-cons-create-handle! hashq-cons-ref hashq-cons-set! hashq-cons
-	    hashq-conser make-gc-buffer))
-
-
-;;; {Eq? hash-consing}
-;;;
-;;; A hash conser maintains a private universe of pairs s.t. if 
-;;; two cons calls pass eq? arguments, the pairs returned are eq?.
-;;;
-;;; A hash conser does not contribute life to the pairs it returns.
-;;;
-
-(define (hashq-cons-hash pair n)
-  (modulo (logxor (hashq (car pair) 4194303)
-		  (hashq (cdr pair) 4194303))
-	  n))
-
-(define (hashq-cons-assoc key l)
-  (and (not (null? l))
-       (or (and (pair? l)		; If not a pair, use its cdr?
-		(pair? (car l))
-		(pair? (caar l))
-		(eq? (car key) (caaar l))
-		(eq? (cdr key) (cdaar l))
-		(car l))
-	   (hashq-cons-assoc key (cdr l)))))
-
-(define (hashq-cons-get-handle table key)
-  (hashx-get-handle hashq-cons-hash hashq-cons-assoc table key))
-
-(define (hashq-cons-create-handle! table key init)
-  (hashx-create-handle! hashq-cons-hash hashq-cons-assoc table key init))
-
-(define (hashq-cons-ref table key)
-  (hashx-ref hashq-cons-hash hashq-cons-assoc table key #f))
-
-(define (hashq-cons-set! table key val)
-  (hashx-set! hashq-cons-hash hashq-cons-assoc table key val))
-
-(define (hashq-cons table a d)
-  (car (hashq-cons-create-handle! table (cons a d) #f)))
-
-(define (hashq-conser hash-tab-or-size)
-  (let ((table (if (vector? hash-tab-or-size)
-		   hash-tab-or-size
-		   (make-doubly-weak-hash-table hash-tab-or-size))))
-    (lambda (a d) (hashq-cons table a d))))
-
-
-
-
-(define (make-gc-buffer n)
-  (let ((ring (make-list n #f)))
-    (append! ring ring)
-    (lambda (next)
-      (set-car! ring next)
-      (set! ring (cdr ring))
-      next)))

module/ice-9/poe.scm

@@ -19,7 +19,6 @@
 
 
 (define-module  (ice-9 poe)
-  #:use-module (ice-9 hcons)
   #:use-module (ice-9 weak-tables)
   #:export (pure-funcq perfect-funcq))
 
@@ -46,6 +45,13 @@
 ;;; are called "pure-funcq", for obvious reasons.
 ;;;
 
+(define (make-gc-buffer n)
+  (let ((ring (make-list n #f)))
+    (append! ring ring)
+    (lambda (next)
+      (set-car! ring next)
+      (set! ring (cdr ring))
+      next)))
 
 (define funcq-memo (make-weak-key-hash-table 523)) ; !!! randomly selected values
 (define funcq-buffer (make-gc-buffer 256))