--- stack/stack.c	2002/03/20 13:20:29	1.118
+++ stack/stack.c	2002/03/27 19:53:01	1.123
@@ -1109,7 +1109,7 @@
   }
 
   if(myenv.interactive) {
-    printf("Stack version $Revision: 1.118 $\n\
+    printf("Stack version $Revision: 1.123 $\n\
 Copyright (C) 2002  Mats Alritzson and Teddy Hogeborn\n\
 Stack comes with ABSOLUTELY NO WARRANTY; for details type 'warranty;'.\n\
 This is free software, and you are welcome to redistribute it\n\
@@ -1651,7 +1651,7 @@
 
   iterator= foo;
 
-  while(iterator!=NULL) {
+  while(iterator->type!=empty) {
     push_val(env, CAR(iterator));
     push_val(env, loop);
     eval(env); if(env->err) return;
@@ -1670,7 +1670,9 @@
 extern void to(environment *env)
 {
   int ending, start, i;
-  value *iterator, *temp;
+  value *iterator, *temp, *end;
+
+  end= new_val(env);
 
   if(env->head->type==empty || CDR(env->head)->type==empty) {
     printerr("Too Few Arguments");
@@ -1705,11 +1707,11 @@
   if(iterator->type==empty
      || (CAR(iterator)->type==symb
 	 && CAR(iterator)->content.sym->id[0]=='[')) {
-    temp= NULL;
+    temp= end;
     toss(env);
   } else {
     /* Search for first delimiter */
-    while(CDR(iterator)!=NULL 
+    while(CDR(iterator)->type!=empty 
 	  && (CAR(CDR(iterator))->type!=symb
 	      || CAR(CDR(iterator))->content.sym->id[0]!='['))
       iterator= CDR(iterator);
@@ -1717,9 +1719,9 @@
     /* Extract list */
     temp= env->head;
     env->head= CDR(iterator);
-    CDR(iterator)= NULL;
+    CDR(iterator)= end;
 
-    if(env->head!=NULL)
+    if(env->head->type!=empty)
       toss(env);
   }
 
@@ -2446,3 +2448,87 @@
   swap(env); if(env->err) return;
   toss(env); if(env->err) return;
 }
+
+/*  2: 3                        =>                */
+/*  1: [ [ 1 . 2 ] [ 3 . 4 ] ]  =>  1: [ 3 . 4 ]  */
+extern void assq(environment *env)
+{
+  assocgen(env, eq);
+}
+
+
+/* General assoc function */
+void assocgen(environment *env, funcp eqfunc)
+{
+  value *key, *item;
+
+  /* Needs two values on the stack, the top one must be an association
+     list */
+  if(env->head->type==empty || CDR(env->head)->type==empty) {
+    printerr("Too Few Arguments");
+    env->err= 1;
+    return;
+  }
+
+  if(CAR(env->head)->type!=tcons) {
+    printerr("Bad Argument Type");
+    env->err= 2;
+    return;
+  }
+
+  key=CAR(CDR(env->head));
+  item=CAR(env->head);
+
+  while(item->type == tcons){
+    if(CAR(item)->type != tcons){
+      printerr("Bad Argument Type");
+      env->err= 2;
+      return;
+    }
+    push_val(env, key);
+    push_val(env, CAR(CAR(item)));
+    eqfunc(env); if(env->err) return;
+
+    /* Check the result of 'eqfunc' */
+    if(env->head->type==empty) {
+      printerr("Too Few Arguments");
+      env->err= 1;
+    return;
+    }
+    if(CAR(env->head)->type!=integer) {
+      printerr("Bad Argument Type");
+      env->err= 2;
+      return;
+    }
+
+    if(CAR(env->head)->content.i){
+      toss(env); if(env->err) return;
+      break;
+    }
+    toss(env); if(env->err) return;
+
+    if(item->type!=tcons) {
+      printerr("Bad Argument Type");
+      env->err= 2;
+      return;
+    }
+
+    item=CDR(item);
+  }
+
+  if(item->type == tcons){	/* A match was found */
+    push_val(env, CAR(item));
+  } else {
+    push_int(env, 0);
+  }
+  swap(env); if(env->err) return;
+  toss(env); if(env->err) return;
+  swap(env); if(env->err) return;
+  toss(env);
+}
+
+extern void sx_646f(environment *env)
+{
+  swap(env); if(env->err) return;
+  eval(env);
+}