--- stack/stack.c	2002/03/20 13:20:29	1.118
+++ stack/stack.c	2002/03/20 17:19:46	1.119
@@ -1109,7 +1109,7 @@
   }
 
   if(myenv.interactive) {
-    printf("Stack version $Revision: 1.118 $\n\
+    printf("Stack version $Revision: 1.119 $\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\
@@ -2446,3 +2446,55 @@
   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)
+{
+  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)));
+    eq(env); if(env->err) return;
+    
+    if(CAR(env->head)->content.i){
+      toss(env);
+      break;
+    }
+    toss(env);
+    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);
+}