--- stack/stack.c	2002/03/17 12:49:27	1.116
+++ stack/stack.c	2003/08/04 13:50:53	1.128
@@ -21,35 +21,6 @@
 	     Teddy Hogeborn <teddy@fukt.bth.se>
 */
 
-#define CAR(X) (X->content.c->car)
-#define CDR(X) (X->content.c->cdr)
-
-/* printf, sscanf, fgets, fprintf, fopen, perror */
-#include <stdio.h>
-/* exit, EXIT_SUCCESS, malloc, free */
-#include <stdlib.h>
-/* NULL */
-#include <stddef.h>
-/* dlopen, dlsym, dlerror */
-#include <dlfcn.h>
-/* strcmp, strcpy, strlen, strcat, strdup */
-#include <string.h>
-/* getopt, STDIN_FILENO, STDOUT_FILENO, usleep */
-#include <unistd.h>
-/* EX_NOINPUT, EX_USAGE */
-#include <sysexits.h>
-/* assert */
-#include <assert.h>
-
-#ifdef __linux__
-/* mtrace, muntrace */
-#include <mcheck.h>
-/* ioctl */
-#include <sys/ioctl.h>
-/* KDMKTONE */
-#include <linux/kd.h>
-#endif /* __linux__ */
-
 #include "stack.h"
 
 /* Initialize a newly created environment */
@@ -62,7 +33,6 @@
   env->gc_ref= NULL;
 
   env->head= new_val(env);
-  env->head->type= empty;
   for(i= 0; i<HASHTBLSIZE; i++)
     env->symbols[i]= NULL;
   env->err= 0;
@@ -77,18 +47,6 @@
   fprintf(stderr, "Err: %s\n", in_string);
 }
 
-/* Discard the top element of the stack. */
-extern void toss(environment *env)
-{
-  if(env->head->type==empty) {
-    printerr("Too Few Arguments");
-    env->err= 1;
-    return;
-  }
-  
-  env->head= CDR(env->head); /* Remove the top stack item */
-}
-
 /* Returns a pointer to a pointer to an element in the hash table. */
 symbol **hash(hashtbl in_hashtbl, const char *in_string)
 {
@@ -124,8 +82,11 @@
   value *nval= malloc(sizeof(value));
   stackitem *nitem= malloc(sizeof(stackitem));
 
+  assert(nval != NULL);
+  assert(nitem != NULL);
+
   nval->content.ptr= NULL;
-  nval->type= integer;
+  nval->type= empty;
 
   nitem->item= nval;
   nitem->next= env->gc_ref;
@@ -139,6 +100,7 @@
   return nval;
 }
 
+
 /* Mark values recursively. 
    Marked values are not collected by the GC. */
 inline void gc_mark(value *val)
@@ -154,13 +116,6 @@
   }
 }
 
-inline void gc_maybe(environment *env)
-{
-  if(env->gc_count < env->gc_limit)
-    return;
-  else
-    return gc_init(env);
-}
 
 /* Start GC */
 extern void gc_init(environment *env)
@@ -203,12 +158,14 @@
       case tcons:
 	free(env->gc_ref->item->content.c);
 	break;
+      case port:
       case empty:
       case integer:
       case tfloat:
       case func:
       case symb:
 	/* Symbol strings are freed when walking the hash table */
+	break;
       }
 
       free(env->gc_ref->item);	/* Remove from gc_ref */
@@ -228,14 +185,14 @@
       printf(" integer: %d", env->gc_ref->item->content.i);
       break;
     case func:
-      printf(" func: %p", env->gc_ref->item->content.ptr);
+      printf(" func: %p", env->gc_ref->item->content.func);
       break;
     case symb:
       printf(" symb: %s", env->gc_ref->item->content.sym->id);
       break;
     case tcons:
-      printf(" tcons: %p\t%p", env->gc_ref->item->content.c->car,
-	     env->gc_ref->item->content.c->cdr);
+      printf(" tcons: %p\t%p", CAR(env->gc_ref->item),
+	     CDR(env->gc_ref->item));
       break;
     default:
       printf(" <unknown %d>", (env->gc_ref->item->type));
@@ -246,7 +203,7 @@
     /* Keep values */     
     env->gc_count += sizeof(value);
     if(env->gc_ref->item->type==string)
-      env->gc_count += strlen(env->gc_ref->item->content.ptr)+1;
+      env->gc_count += strlen(env->gc_ref->item->content.string)+1;
     
     titem= env->gc_ref->next;
     env->gc_ref->next= new_head;
@@ -265,6 +222,14 @@
 
 }
 
+inline void gc_maybe(environment *env)
+{
+  if(env->gc_count < env->gc_limit)
+    return;
+  else
+    return gc_init(env);
+}
+
 /* Protect values from GC */
 void protect(value *val)
 {
@@ -335,9 +300,10 @@
   value *new_value= new_val(env);
   int length= strlen(in_string)+1;
 
-  new_value->content.ptr= malloc(length);
+  new_value->content.string= malloc(length);
+  assert(new_value != NULL);
   env->gc_count += length;
-  strcpy(new_value->content.ptr, in_string);
+  strcpy(new_value->content.string, in_string);
   new_value->type= string;
 
   push_val(env, new_value);
@@ -350,6 +316,7 @@
   char *new_string, *current;
 
   new_string= malloc((strlen(old_string)*2)+4);
+  assert(new_string != NULL);
   strcpy(new_string, "sx_");	/* Stack eXternal */
   current= new_string+3;
   while(old_string[0] != '\0'){
@@ -379,8 +346,7 @@
     return;
   }
 
-  new_string= 
-    mangle_str((const char *)(CAR(env->head)->content.ptr));
+  new_string= mangle_str(CAR(env->head)->content.string);
 
   toss(env);
   if(env->err) return;
@@ -419,9 +385,11 @@
 
     /* Create a new symbol */
     (*new_symbol)= malloc(sizeof(symbol));
+    assert((*new_symbol) != NULL);
     (*new_symbol)->val= NULL;	/* undefined value */
     (*new_symbol)->next= NULL;
     (*new_symbol)->id= malloc(strlen(in_string)+1);
+    assert((*new_symbol)->id != NULL);
     strcpy((*new_symbol)->id, in_string);
 
     /* Intern the new symbol in the hash table */
@@ -443,7 +411,7 @@
 
     if(dlerr==NULL) {		/* If a function was found */
       new_fvalue->type= func;	/* The new value is a function pointer */
-      new_fvalue->content.ptr= funcptr; /* Store function pointer */
+      new_fvalue->content.func= funcptr; /* Store function pointer */
       (*new_symbol)->val= new_fvalue; /* Bind the symbol to the new
                                          function value */
     }
@@ -455,151 +423,155 @@
   unprotect(new_value); unprotect(new_fvalue);
 }
 
-/* Print newline. */
-extern void nl()
-{
-  printf("\n");
-}
-
-/* Gets the type of a value */
-extern void type(environment *env)
-{
-  if(env->head->type==empty) {
-    printerr("Too Few Arguments");
-    env->err= 1;
-    return;
-  }
-
-  switch(CAR(env->head)->type){
-  case empty:
-    push_sym(env, "empty");
-    break;
-  case integer:
-    push_sym(env, "integer");
-    break;
-  case tfloat:
-    push_sym(env, "float");
-    break;
-  case string:
-    push_sym(env, "string");
-    break;
-  case symb:
-    push_sym(env, "symbol");
-    break;
-  case func:
-    push_sym(env, "function");
-    break;
-  case tcons:
-    push_sym(env, "pair");
-    break;
-  }
-  swap(env);
-  if (env->err) return;
-  toss(env);
-}    
-
 /* Print a value */
-void print_val(value *val, int noquote)
+void print_val(environment *env, value *val, int noquote, stackitem *stack, FILE *stream)
 {
+  stackitem *titem, *tstack;
+  int depth;
+
   switch(val->type) {
   case empty:
-    printf("[]");
+    if(fprintf(stream, "[]") < 0){
+      perror("print_val");
+      env->err= 5;
+      return;
+    }
     break;
   case integer:
-    printf("%d", val->content.i);
+    if(fprintf(stream, "%d", val->content.i) < 0){
+      perror("print_val");
+      env->err= 5;
+      return;
+    }
     break;
   case tfloat:
-    printf("%f", val->content.f);
+    if(fprintf(stream, "%f", val->content.f) < 0){
+      perror("print_val");
+      env->err= 5;
+      return;
+    }
     break;
   case string:
-    if(noquote)
-      printf("%s", (char*)(val->content.ptr));
-    else
-      printf("\"%s\"", (char*)(val->content.ptr));
+    if(noquote){
+      if(fprintf(stream, "%s", val->content.string) < 0){
+	perror("print_val");
+	env->err= 5;
+	return;
+      }
+    } else {			/* quote */
+      if(fprintf(stream, "\"%s\"", val->content.string) < 0){
+	perror("print_val");
+	env->err= 5;
+	return;
+      }
+    }
     break;
   case symb:
-    printf("%s", val->content.sym->id);
+    if(fprintf(stream, "%s", val->content.sym->id) < 0){
+      perror("print_val");
+      env->err= 5;
+      return;
+    }
     break;
   case func:
-    printf("#<function %p>", (funcp)(val->content.ptr));
+    if(fprintf(stream, "#<function %p>", val->content.func) < 0){
+      perror("print_val");
+      env->err= 5;
+      return;
+    }
+    break;
+  case port:
+    if(fprintf(stream, "#<port %p>", val->content.p) < 0){
+      perror("print_val");
+      env->err= 5;
+      return;
+    }
     break;
   case tcons:
-    printf("[ ");
+    if(fprintf(stream, "[ ") < 0){
+      perror("print_val");
+      env->err= 5;
+      return;
+    }
+    tstack= stack;
     do {
-      print_val(CAR(val), noquote);
+      titem=malloc(sizeof(stackitem));
+      assert(titem != NULL);
+      titem->item=val;
+      titem->next=tstack;
+      tstack=titem;		/* Put it on the stack */
+      /* Search a stack of values being printed to see if we are already
+	 printing this value */
+      titem=tstack;
+      depth=0;
+      while(titem != NULL && titem->item != CAR(val)){
+	titem=titem->next;
+	depth++;
+      }
+      if(titem != NULL){	/* If we found it on the stack, */
+	if(fprintf(stream, "#%d#", depth) < 0){	/* print a depth reference */
+	  perror("print_val");
+	  env->err= 5;
+	  free(titem);
+	  return;
+	}
+      } else {
+	print_val(env, CAR(val), noquote, tstack, stream);
+      }
       val= CDR(val);
       switch(val->type){
       case empty:
 	break;
       case tcons:
-	printf(" ");
+	/* Search a stack of values being printed to see if we are already
+	   printing this value */
+	titem=tstack;
+	depth=0;
+	while(titem != NULL && titem->item != val){
+	  titem=titem->next;
+	  depth++;
+	}
+	if(titem != NULL){	/* If we found it on the stack, */
+	  if(fprintf(stream, " . #%d#", depth) < 0){ /* print a depth reference */
+	    perror("print_val");
+	    env->err= 5;
+	    goto printval_end;
+	  }
+	} else {
+	  if(fprintf(stream, " ") < 0){
+	    perror("print_val");
+	    env->err= 5;
+	    goto printval_end;
+	  }
+	}
 	break;
       default:
-	printf(" . ");		/* Improper list */
-	print_val(val, noquote);
+	if(fprintf(stream, " . ") < 0){	/* Improper list */
+	  perror("print_val");
+	  env->err= 5;
+	  goto printval_end;
+        }
+	print_val(env, val, noquote, tstack, stream);
       }
-    } while(val->type == tcons);
-    printf(" ]");
-    break;
-  }
-}
+    } while(val->type == tcons && titem == NULL);
 
-extern void print_(environment *env)
-{
-  if(env->head->type==empty) {
-    printerr("Too Few Arguments");
-    env->err= 1;
-    return;
-  }
-  print_val(CAR(env->head), 0);
-  nl();
-}
-
-/* Prints the top element of the stack and then discards it. */
-extern void print(environment *env)
-{
-  print_(env);
-  if(env->err) return;
-  toss(env);
-}
+  printval_end:
 
-extern void princ_(environment *env)
-{
-  if(env->head->type==empty) {
-    printerr("Too Few Arguments");
-    env->err= 1;
-    return;
-  }
-  print_val(CAR(env->head), 1);
-}
-
-/* Prints the top element of the stack and then discards it. */
-extern void princ(environment *env)
-{
-  princ_(env);
-  if(env->err) return;
-  toss(env);
-}
-
-/* Only to be called by function printstack. */
-void print_st(value *stack_head, long counter)
-{ 
-  if(CDR(stack_head)->type != empty)
-    print_st(CDR(stack_head), counter+1);
-  printf("%ld: ", counter);
-  print_val(CAR(stack_head), 0);
-  nl();
-}
+    titem=tstack;
+    while(titem != stack){
+      tstack=titem->next;
+      free(titem);
+      titem=tstack;
+    }
 
-/* Prints the stack. */
-extern void printstack(environment *env)
-{
-  if(env->head->type == empty) {
-    printf("Stack Empty\n");
-    return;
+    if(! (env->err)){
+      if(fprintf(stream, " ]") < 0){
+	perror("print_val");
+	env->err= 5;
+      }
+    }
+    break;
   }
-
-  print_st(env->head, 1);
 }
 
 /* Swap the two top elements on the stack. */
@@ -618,23 +590,6 @@
   CDR(env->head)= temp;
 } 
 
-/* Rotate the first three elements on the stack. */
-extern void rot(environment *env)
-{
-  value *temp= env->head;
-  
-  if(env->head->type == empty || CDR(env->head)->type == empty
-     || CDR(CDR(env->head))->type == empty) {
-    printerr("Too Few Arguments");
-    env->err= 1;
-    return;
-  }
-  
-  env->head= CDR(CDR(env->head));
-  CDR(CDR(temp))= CDR(env->head);
-  CDR(env->head)= temp;
-}
-
 /* Recall a value from a symbol, if bound */
 extern void rcl(environment *env)
 {
@@ -665,6 +620,7 @@
   if(env->err) return;
 }
 
+
 /* If the top element is a symbol, determine if it's bound to a
    function value, and if it is, toss the symbol and execute the
    function. */
@@ -696,7 +652,7 @@
 
     /* If it's a lone function value, run it */
   case func:
-    in_func= (funcp)(CAR(env->head)->content.ptr);
+    in_func= CAR(env->head)->content.func;
     toss(env); 
     if(env->err) return;
     return in_func(env);
@@ -735,207 +691,41 @@
     return;
 
   case empty:
+    toss(env); 
   case integer:
   case tfloat:
   case string:
+  case port:
     return;
   }
 }
 
-/* Reverse (flip) a list */
-extern void rev(environment *env)
-{
-  value *old_head, *new_head, *item;
-
-  if(env->head->type==empty) {
-    printerr("Too Few Arguments");
-    env->err= 1;
-    return;
-  }
-
-  if(CAR(env->head)->type==empty)
-    return;			/* Don't reverse an empty list */
-
-  if(CAR(env->head)->type!=tcons) {
-    printerr("Bad Argument Type");
-    env->err= 2;
-    return;
-  }
-
-  old_head= CAR(env->head);
-  new_head= new_val(env);
-  new_head->type= empty;
-  while(old_head->type != empty) {
-    item= old_head;
-    old_head= CDR(old_head);
-    CDR(item)= new_head;
-    new_head= item;
-  }
-  CAR(env->head)= new_head;
-}
-
-/* Make a list. */
-extern void pack(environment *env)
-{
-  value *iterator, *temp, *ending;
-
-  ending=new_val(env);
-  ending->type=empty;
-
-  iterator= env->head;
-  if(iterator->type == empty
-     || (CAR(iterator)->type==symb
-     && CAR(iterator)->content.sym->id[0]=='[')) {
-    temp= ending;
-    toss(env);
-  } else {
-    /* Search for first delimiter */
-    while(CDR(iterator)->type != empty
-	  && (CAR(CDR(iterator))->type!=symb
-	   || CAR(CDR(iterator))->content.sym->id[0]!='['))
-      iterator= CDR(iterator);
-    
-    /* Extract list */
-    temp= env->head;
-    env->head= CDR(iterator);
-    CDR(iterator)= ending;
-
-    if(env->head->type != empty)
-      toss(env);
-  }
-
-  /* Push list */
-
-  push_val(env, temp);
-  rev(env);
-}
-
-/* Relocate elements of the list on the stack. */
-extern void expand(environment *env)
+/* List all defined words */
+extern void words(environment *env)
 {
-  value *temp, *new_head;
-
-  /* Is top element a list? */
-  if(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;
-  }
-
-  rev(env);
-
-  if(env->err)
-    return;
-
-  /* The first list element is the new stack head */
-  new_head= temp= CAR(env->head);
-
-  toss(env);
-
-  /* Find the end of the list */
-  while(CDR(temp)->type != empty) {
-    if (CDR(temp)->type == tcons)
-      temp= CDR(temp);
-    else {
-      printerr("Bad Argument Type"); /* Improper list */
-      env->err= 2;
-      return;
+  symbol *temp;
+  int i;
+  
+  for(i= 0; i<HASHTBLSIZE; i++) {
+    temp= env->symbols[i];
+    while(temp!=NULL) {
+#ifdef DEBUG
+      if (temp->val != NULL && temp->val->gc.flag.protect)
+	printf("(protected) ");
+#endif /* DEBUG */
+      printf("%s ", temp->id);
+      temp= temp->next;
     }
   }
-
-  /* Connect the tail of the list with the old stack head */
-  CDR(temp)= env->head;
-  env->head= new_head;		/* ...and voila! */
-
-}
-
-/* Compares two elements by reference. */
-extern void eq(environment *env)
-{
-  void *left, *right;
-
-  if(env->head->type==empty || CDR(env->head)->type==empty) {
-    printerr("Too Few Arguments");
-    env->err= 1;
-    return;
-  }
-
-  left= CAR(env->head)->content.ptr;
-  right= CAR(CDR(env->head))->content.ptr;
-  toss(env); toss(env);
-
-  push_int(env, left==right);
-}
-
-/* Negates the top element on the stack. */
-extern void not(environment *env)
-{
-  int val;
-
-  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;
-  }
-
-  val= CAR(env->head)->content.i;
-  toss(env);
-  push_int(env, !val);
 }
 
-/* Compares the two top elements on the stack and return 0 if they're the
-   same. */
-extern void neq(environment *env)
-{
-  eq(env);
-  not(env);
-}
-
-/* Give a symbol some content. */
-extern void def(environment *env)
-{
-  symbol *sym;
-
-  /* Needs two values on the stack, the top one must be a symbol */
-  if(env->head->type==empty || CDR(env->head)->type==empty) {
-    printerr("Too Few Arguments");
-    env->err= 1;
-    return;
-  }
-
-  if(CAR(env->head)->type!=symb) {
-    printerr("Bad Argument Type");
-    env->err= 2;
-    return;
-  }
-
-  /* long names are a pain */
-  sym= CAR(env->head)->content.ptr;
-
-  /* Bind the symbol to the value */
-  sym->val= CAR(CDR(env->head));
-
-  toss(env); toss(env);
-} 
-
 /* Quit stack. */
 extern void quit(environment *env)
 {
   int i;
 
-  clear(env);
+  while(env->head->type != empty)
+    toss(env);
 
   if (env->err) return;
   for(i= 0; i<HASHTBLSIZE; i++) {
@@ -960,32 +750,6 @@
   exit(EXIT_SUCCESS);
 }
 
-/* Clear stack */
-extern void clear(environment *env)
-{
-  while(env->head->type != empty)
-    toss(env);
-}
-
-/* List all defined words */
-extern void words(environment *env)
-{
-  symbol *temp;
-  int i;
-  
-  for(i= 0; i<HASHTBLSIZE; i++) {
-    temp= env->symbols[i];
-    while(temp!=NULL) {
-#ifdef DEBUG
-      if (temp->val != NULL && temp->val->gc.flag.protect)
-	printf("(protected) ");
-#endif /* DEBUG */
-      printf("%s\n", temp->id);
-      temp= temp->next;
-    }
-  }
-}
-
 /* Internal forget function */
 void forget_sym(symbol **hash_entry)
 {
@@ -998,33 +762,25 @@
   free(temp);
 }
 
-/* Forgets a symbol (remove it from the hash table) */
-extern void forget(environment *env)
-{
-  char* sym_id;
+/* Only to be called by itself function printstack. */
+void print_st(environment *env, value *stack_head, long counter)
+{ 
+  if(CDR(stack_head)->type != empty)
+    print_st(env, CDR(stack_head), counter+1);
+  printf("%ld: ", counter);
+  print_val(env, CAR(stack_head), 0, NULL, stdout);
+  printf("\n");
+}
 
-  if(env->head->type==empty) {
-    printerr("Too Few Arguments");
-    env->err= 1;
-    return;
-  }
-  
-  if(CAR(env->head)->type!=symb) {
-    printerr("Bad Argument Type");
-    env->err= 2;
+/* Prints the stack. */
+extern void printstack(environment *env)
+{
+  if(env->head->type == empty) {
+    printf("Stack Empty\n");
     return;
   }
 
-  sym_id= CAR(env->head)->content.sym->id;
-  toss(env);
-
-  return forget_sym(hash(env->symbols, sym_id));
-}
-
-/* Returns the current error number to the stack */
-extern void errn(environment *env)
-{
-  push_int(env, env->err);
+  print_st(env, env->head, 1);
 }
 
 int main(int argc, char **argv)
@@ -1066,7 +822,7 @@
   }
 
   if(myenv.interactive) {
-    printf("Stack version $Revision: 1.116 $\n\
+    printf("Stack version $Revision: 1.128 $\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\
@@ -1078,252 +834,31 @@
       if (myenv.interactive) {
 	if(myenv.err) {
 	  printf("(error %d)\n", myenv.err);
+	  myenv.err= 0;
 	}
-	nl();
+	printf("\n");
 	printstack(&myenv);
 	printf("> ");
       }
       myenv.err=0;
     }
-    sx_72656164(&myenv);	/* "read" */
-    if (myenv.err==4) {		/* EOF */
+    readstream(&myenv, myenv.inputstream);
+    if (myenv.err) {		/* EOF or other error */
       myenv.err=0;
       quit(&myenv);
     } else if(myenv.head->type!=empty
 	      && CAR(myenv.head)->type==symb
-	      && CAR(myenv.head)->content.sym->id[0]
-	      ==';') {
-      toss(&myenv); 		/* No error check in main */
+	      && CAR(myenv.head)->content.sym->id[0] == ';') {
+      toss(&myenv); if(myenv.err) continue;
       eval(&myenv);
+    } else {
+      gc_maybe(&myenv);
     }
-    gc_maybe(&myenv);
   }
   quit(&myenv);
   return EXIT_FAILURE;
 }
 
-/* "+" */
-extern void sx_2b(environment *env)
-{
-  int a, b;
-  float fa, fb;
-  size_t len;
-  char* new_string;
-  value *a_val, *b_val;
-
-  if(env->head->type==empty || CDR(env->head)->type==empty) {
-    printerr("Too Few Arguments");
-    env->err= 1;
-    return;
-  }
-
-  if(CAR(env->head)->type==string
-     && CAR(CDR(env->head))->type==string) {
-    a_val= CAR(env->head);
-    b_val= CAR(CDR(env->head));
-    protect(a_val); protect(b_val);
-    toss(env); if(env->err) return;
-    toss(env); if(env->err) return;
-    len= strlen(a_val->content.ptr)+strlen(b_val->content.ptr)+1;
-    new_string= malloc(len);
-    strcpy(new_string, b_val->content.ptr);
-    strcat(new_string, a_val->content.ptr);
-    push_cstring(env, new_string);
-    unprotect(a_val); unprotect(b_val);
-    free(new_string);
-    
-    return;
-  }
-  
-  if(CAR(env->head)->type==integer
-     && CAR(CDR(env->head))->type==integer) {
-    a= CAR(env->head)->content.i;
-    toss(env); if(env->err) return;
-    b= CAR(env->head)->content.i;
-    toss(env); if(env->err) return;
-    push_int(env, b+a);
-
-    return;
-  }
-
-  if(CAR(env->head)->type==tfloat
-     && CAR(CDR(env->head))->type==tfloat) {
-    fa= CAR(env->head)->content.f;
-    toss(env); if(env->err) return;
-    fb= CAR(env->head)->content.f;
-    toss(env); if(env->err) return;
-    push_float(env, fb+fa);
-    
-    return;
-  }
-
-  if(CAR(env->head)->type==tfloat
-     && CAR(CDR(env->head))->type==integer) {
-    fa= CAR(env->head)->content.f;
-    toss(env); if(env->err) return;
-    b= CAR(env->head)->content.i;
-    toss(env); if(env->err) return;
-    push_float(env, b+fa);
-    
-    return;
-  }
-
-  if(CAR(env->head)->type==integer
-     && CAR(CDR(env->head))->type==tfloat) {
-    a= CAR(env->head)->content.i;
-    toss(env); if(env->err) return;
-    fb= CAR(env->head)->content.f;
-    toss(env); if(env->err) return;
-    push_float(env, fb+a);
-
-    return;
-  }
-
-  printerr("Bad Argument Type");
-  env->err=2;
-}
-
-/* "-" */
-extern void sx_2d(environment *env)
-{
-  int a, b;
-  float fa, fb;
-
-  if(env->head->type==empty || CDR(env->head)->type==empty) {
-    printerr("Too Few Arguments");
-    env->err=1;
-    return;
-  }
-  
-  if(CAR(env->head)->type==integer
-     && CAR(CDR(env->head))->type==integer) {
-    a= CAR(env->head)->content.i;
-    toss(env); if(env->err) return;
-    b= CAR(env->head)->content.i;
-    toss(env); if(env->err) return;
-    push_int(env, b-a);
-
-    return;
-  }
-
-  if(CAR(env->head)->type==tfloat
-     && CAR(CDR(env->head))->type==tfloat) {
-    fa= CAR(env->head)->content.f;
-    toss(env); if(env->err) return;
-    fb= CAR(env->head)->content.f;
-    toss(env); if(env->err) return;
-    push_float(env, fb-fa);
-    
-    return;
-  }
-
-  if(CAR(env->head)->type==tfloat
-     && CAR(CDR(env->head))->type==integer) {
-    fa= CAR(env->head)->content.f;
-    toss(env); if(env->err) return;
-    b= CAR(env->head)->content.i;
-    toss(env); if(env->err) return;
-    push_float(env, b-fa);
-    
-    return;
-  }
-
-  if(CAR(env->head)->type==integer
-     && CAR(CDR(env->head))->type==tfloat) {
-    a= CAR(env->head)->content.i;
-    toss(env); if(env->err) return;
-    fb= CAR(env->head)->content.f;
-    toss(env); if(env->err) return;
-    push_float(env, fb-a);
-
-    return;
-  }
-
-  printerr("Bad Argument Type");
-  env->err=2;
-}
-
-/* ">" */
-extern void sx_3e(environment *env)
-{
-  int a, b;
-  float fa, fb;
-
-  if(env->head->type==empty || CDR(env->head)->type==empty) {
-    printerr("Too Few Arguments");
-    env->err= 1;
-    return;
-  }
-  
-  if(CAR(env->head)->type==integer
-     && CAR(CDR(env->head))->type==integer) {
-    a= CAR(env->head)->content.i;
-    toss(env); if(env->err) return;
-    b= CAR(env->head)->content.i;
-    toss(env); if(env->err) return;
-    push_int(env, b>a);
-
-    return;
-  }
-
-  if(CAR(env->head)->type==tfloat
-     && CAR(CDR(env->head))->type==tfloat) {
-    fa= CAR(env->head)->content.f;
-    toss(env); if(env->err) return;
-    fb= CAR(env->head)->content.f;
-    toss(env); if(env->err) return;
-    push_int(env, fb>fa);
-    
-    return;
-  }
-
-  if(CAR(env->head)->type==tfloat
-     && CAR(CDR(env->head))->type==integer) {
-    fa= CAR(env->head)->content.f;
-    toss(env); if(env->err) return;
-    b= CAR(env->head)->content.i;
-    toss(env); if(env->err) return;
-    push_int(env, b>fa);
-    
-    return;
-  }
-
-  if(CAR(env->head)->type==integer
-     && CAR(CDR(env->head))->type==tfloat) {
-    a= CAR(env->head)->content.i;
-    toss(env); if(env->err) return;
-    fb= CAR(env->head)->content.f;
-    toss(env); if(env->err) return;
-    push_int(env, fb>a);
-
-    return;
-  }
-
-  printerr("Bad Argument Type");
-  env->err= 2;
-}
-
-/* "<" */
-extern void sx_3c(environment *env) 
-{
-  swap(env); if(env->err) return;
-  sx_3e(env);
-}
-
-/* "<=" */
-extern void sx_3c3d(environment *env)
-{
-  sx_3e(env); if(env->err) return;
-  not(env);
-}
-
-/* ">=" */
-extern void sx_3e3d(environment *env)
-{
-  sx_3c(env); if(env->err) return;
-  not(env);
-}
-
 /* Return copy of a value */
 value *copy_val(environment *env, value *old_value)
 {
@@ -1332,7 +867,6 @@
   if(old_value==NULL)
     return NULL;
 
-  protect(old_value);
   new_value= new_val(env);
   new_value->type= old_value->type;
 
@@ -1342,11 +876,11 @@
   case func:
   case symb:
   case empty:
+  case port:
     new_value->content= old_value->content;
     break;
   case string:
-    (char *)(new_value->content.ptr)= 
-      strdup((char *)(old_value->content.ptr));
+    new_value->content.string= strdup(old_value->content.string);
     break;
   case tcons:
 
@@ -1359,343 +893,93 @@
     break;
   }
 
-  unprotect(old_value);
-
   return new_value;
 }
 
-/* "dup"; duplicates an item on the stack */
-extern void sx_647570(environment *env)
-{
-  if(env->head->type==empty) {
-    printerr("Too Few Arguments");
-    env->err= 1;
-    return;
-  }
-  push_val(env, copy_val(env, CAR(env->head)));
-}
-
-/* "if", If-Then */
-extern void sx_6966(environment *env)
-{
-  int truth;
-
-  if(env->head->type==empty || CDR(env->head)->type==empty) {
-    printerr("Too Few Arguments");
-    env->err= 1;
-    return;
-  }
-
-  if(CAR(CDR(env->head))->type != integer) {
-    printerr("Bad Argument Type");
-    env->err= 2;
-    return;
-  }
-  
-  swap(env);
-  if(env->err) return;
-  
-  truth= CAR(env->head)->content.i;
-
-  toss(env);
-  if(env->err) return;
-
-  if(truth)
-    eval(env);
-  else
-    toss(env);
-}
-
-/* If-Then-Else */
-extern void ifelse(environment *env)
-{
-  int truth;
-
-  if(env->head->type==empty || CDR(env->head)->type==empty
-     || CDR(CDR(env->head))->type==empty) {
-    printerr("Too Few Arguments");
-    env->err= 1;
-    return;
-  }
-
-  if(CAR(CDR(CDR(env->head)))->type!=integer) {
-    printerr("Bad Argument Type");
-    env->err= 2;
-    return;
-  }
-  
-  rot(env);
-  if(env->err) return;
-  
-  truth= CAR(env->head)->content.i;
-
-  toss(env);
-  if(env->err) return;
-
-  if(!truth)
-    swap(env);
-  if(env->err) return;
-
-  toss(env);
-  if(env->err) return;
-
-  eval(env);
-}
-
-extern void sx_656c7365(environment *env)
+/* read a line from a stream; used by readline */
+void readlinestream(environment *env, FILE *stream)
 {
-  if(env->head->type==empty || CDR(env->head)->type==empty 
-     || CDR(CDR(env->head))->type==empty || CDR(CDR(CDR(env->head)))->type==empty
-     || CDR(CDR(CDR(CDR(env->head))))->type==empty) {
-    printerr("Too Few Arguments");
-    env->err= 1;
-    return;
-  }
-
-  if(CAR(CDR(env->head))->type!=symb
-     || strcmp(CAR(CDR(env->head))->content.sym->id, "then")!=0
-     || CAR(CDR(CDR(CDR(env->head))))->type!=symb
-     || strcmp(CAR(CDR(CDR(CDR(env->head))))->content.sym->id, "if")!=0) {
-    printerr("Bad Argument Type");
-    env->err= 2;
-    return;
-  }
-
-  swap(env); toss(env); rot(env); toss(env);
-  ifelse(env);
-}
-
-extern void then(environment *env)
-{
-  if(env->head->type==empty || CDR(env->head)->type==empty
-     || CDR(CDR(env->head))->type==empty) { 
-    printerr("Too Few Arguments");
-    env->err= 1;
-    return;
-  }
-
-  if(CAR(CDR(env->head))->type!=symb
-     || strcmp(CAR(CDR(env->head))->content.sym->id, "if")!=0) {
-    printerr("Bad Argument Type");
-    env->err= 2;
-    return;
-  }
-
-  swap(env); toss(env);
-  sx_6966(env);
-}
-
-/* "while" */
-extern void sx_7768696c65(environment *env)
-{
-  int truth;
-  value *loop, *test;
-
-  if(env->head->type==empty || CDR(env->head)->type==empty) {
-    printerr("Too Few Arguments");
-    env->err= 1;
-    return;
-  }
-
-  loop= CAR(env->head);
-  protect(loop);
-  toss(env); if(env->err) return;
-
-  test= CAR(env->head);
-  protect(test);
-  toss(env); if(env->err) return;
+  char in_string[101];
 
-  do {
-    push_val(env, test);
-    eval(env);
-    
-    if(CAR(env->head)->type != integer) {
-      printerr("Bad Argument Type");
-      env->err= 2;
-      return;
-    }
-    
-    truth= CAR(env->head)->content.i;
-    toss(env); if(env->err) return;
-    
-    if(truth) {
-      push_val(env, loop);
-      eval(env);
-    } else {
-      toss(env);
+  if(fgets(in_string, 100, stream)==NULL) {
+    push_cstring(env, "");
+    if (! feof(stream)){
+      perror("readline");
+      env->err= 5;
     }
-  
-  } while(truth);
-
-  unprotect(loop); unprotect(test);
+  } else {
+    push_cstring(env, in_string);
+  }
 }
 
-
-/* "for"; for-loop */
-extern void sx_666f72(environment *env)
+/* Reverse (flip) a list */
+extern void rev(environment *env)
 {
-  value *loop;
-  int foo1, foo2;
+  value *old_head, *new_head, *item;
 
-  if(env->head->type==empty || CDR(env->head)->type==empty 
-     || CDR(CDR(env->head))->type==empty) {
+  if(env->head->type==empty) {
     printerr("Too Few Arguments");
     env->err= 1;
     return;
   }
 
-  if(CAR(CDR(env->head))->type!=integer
-     || CAR(CDR(CDR(env->head)))->type!=integer) {
-    printerr("Bad Argument Type");
-    env->err= 2;
-    return;
-  }
-
-  loop= CAR(env->head);
-  protect(loop);
-  toss(env); if(env->err) return;
-
-  foo2= CAR(env->head)->content.i;
-  toss(env); if(env->err) return;
-
-  foo1= CAR(env->head)->content.i;
-  toss(env); if(env->err) return;
-
-  if(foo1<=foo2) {
-    while(foo1<=foo2) {
-      push_int(env, foo1);
-      push_val(env, loop);
-      eval(env); if(env->err) return;
-      foo1++;
-    }
-  } else {
-    while(foo1>=foo2) {
-      push_int(env, foo1);
-      push_val(env, loop);
-      eval(env); if(env->err) return;
-      foo1--;
-    }
-  }
-  unprotect(loop);
-}
-
-/* Variant of for-loop */
-extern void foreach(environment *env)
-{  
-  value *loop, *foo;
-  value *iterator;
-  
-  if(env->head->type==empty || CDR(env->head)->type==empty) {
-    printerr("Too Few Arguments");
-    env->err= 1;
-    return;
-  }
+  if(CAR(env->head)->type==empty)
+    return;			/* Don't reverse an empty list */
 
-  if(CAR(CDR(env->head))->type!=tcons) {
+  if(CAR(env->head)->type!=tcons) {
     printerr("Bad Argument Type");
     env->err= 2;
     return;
   }
 
-  loop= CAR(env->head);
-  protect(loop);
-  toss(env); if(env->err) return;
-
-  foo= CAR(env->head);
-  protect(foo);
-  toss(env); if(env->err) return;
-
-  iterator= foo;
-
-  while(iterator!=NULL) {
-    push_val(env, CAR(iterator));
-    push_val(env, loop);
-    eval(env); if(env->err) return;
-    if (iterator->type == tcons){
-      iterator= CDR(iterator);
-    } else {
-      printerr("Bad Argument Type"); /* Improper list */
-      env->err= 2;
-      break;
-    }
+  old_head= CAR(env->head);
+  new_head= new_val(env);
+  while(old_head->type != empty) {
+    item= old_head;
+    old_head= CDR(old_head);
+    CDR(item)= new_head;
+    new_head= item;
   }
-  unprotect(loop); unprotect(foo);
+  CAR(env->head)= new_head;
 }
 
-/* "to" */
-extern void to(environment *env)
+/* Make a list. */
+extern void pack(environment *env)
 {
-  int ending, start, i;
-  value *iterator, *temp;
-
-  if(env->head->type==empty || CDR(env->head)->type==empty) {
-    printerr("Too Few Arguments");
-    env->err= 1;
-    return;
-  }
-
-  if(CAR(env->head)->type!=integer 
-     || CAR(CDR(env->head))->type!=integer) {
-    printerr("Bad Argument Type");
-    env->err= 2;
-    return;
-  }
-
-  ending= CAR(env->head)->content.i;
-  toss(env); if(env->err) return;
-  start= CAR(env->head)->content.i;
-  toss(env); if(env->err) return;
-
-  push_sym(env, "[");
+  value *iterator, *temp, *ending;
 
-  if(ending>=start) {
-    for(i= ending; i>=start; i--)
-      push_int(env, i);
-  } else {
-    for(i= ending; i<=start; i++)
-      push_int(env, i);
-  }
+  ending=new_val(env);
 
   iterator= env->head;
-
-  if(iterator->type==empty
+  if(iterator->type == empty
      || (CAR(iterator)->type==symb
-	 && CAR(iterator)->content.sym->id[0]=='[')) {
-    temp= NULL;
+     && CAR(iterator)->content.sym->id[0]=='[')) {
+    temp= ending;
     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]!='['))
+	   || CAR(CDR(iterator))->content.sym->id[0]!='['))
       iterator= CDR(iterator);
     
     /* Extract list */
     temp= env->head;
     env->head= CDR(iterator);
-    CDR(iterator)= NULL;
+    CDR(iterator)= ending;
 
-    if(env->head!=NULL)
+    if(env->head->type != empty)
       toss(env);
   }
 
   /* Push list */
-  push_val(env, temp);
-}
-
-/* Read a string */
-extern void readline(environment *env)
-{
-  char in_string[101];
 
-  if(fgets(in_string, 100, env->inputstream)==NULL)
-    push_cstring(env, "");
-  else
-    push_cstring(env, in_string);
+  push_val(env, temp);
+  rev(env);
 }
 
-/* "read"; Read a value and place on stack */
-extern void sx_72656164(environment *env)
+/* read from a stream; used by "read" and "readport" */
+void readstream(environment *env, FILE *stream)
 {
   const char symbform[]= "%[a-zA-Z0-9!$%*+./:<=>?@^_~-]%n";
   const char strform[]= "\"%[^\"]\"%n";
@@ -1717,21 +1001,24 @@
     if(depth > 0 && env->interactive) {
       printf("]> ");
     }
-    readline(env); if(env->err) return;
+    readlinestream(env, env->inputstream);
+    if(env->err) return;
 
-    if(((char *)(CAR(env->head)->content.ptr))[0]=='\0'){
+    if((CAR(env->head)->content.string)[0]=='\0'){
       env->err= 4;		/* "" means EOF */
       return;
     }
     
-    env->in_string= malloc(strlen(CAR(env->head)->content.ptr)+1);
+    env->in_string= malloc(strlen(CAR(env->head)->content.string)+1);
+    assert(env->in_string != NULL);
     env->free_string= env->in_string; /* Save the original pointer */
-    strcpy(env->in_string, CAR(env->head)->content.ptr);
+    strcpy(env->in_string, CAR(env->head)->content.string);
     toss(env); if(env->err) return;
   }
   
   inlength= strlen(env->in_string)+1;
   match= malloc(inlength);
+  assert(match != NULL);
 
   if(sscanf(env->in_string, blankform, &readlength) != EOF
      && readlength != -1) {
@@ -1775,75 +1062,7 @@
   free(match);
 
   if(depth)
-    return sx_72656164(env);
-}
-
-#ifdef __linux__
-extern void beep(environment *env)
-{
-  int freq, dur, period, ticks;
-
-  if(env->head->type==empty || CDR(env->head)->type==empty) {
-    printerr("Too Few Arguments");
-    env->err= 1;
-    return;
-  }
-
-  if(CAR(env->head)->type!=integer
-     || CAR(CDR(env->head))->type!=integer) {
-    printerr("Bad Argument Type");
-    env->err= 2;
-    return;
-  }
-
-  dur= CAR(env->head)->content.i;
-  toss(env);
-  freq= CAR(env->head)->content.i;
-  toss(env);
-
-  period= 1193180/freq;		/* convert freq from Hz to period
-                                   length */
-  ticks= dur*.001193180;	/* convert duration from µseconds to
-				   timer ticks */
-
-/*    ticks=dur/1000; */
-
-      /*  if (ioctl(STDOUT_FILENO, KDMKTONE, (125<<16) + 0x637)==0) */
-  switch (ioctl(STDOUT_FILENO, KDMKTONE, (ticks<<16) | period)){
-  case 0:
-    usleep(dur);
-    return;
-  case -1:
-    perror("beep");
-    env->err= 5;
-    return;
-  default:
-    abort();
-  }
-}
-#endif /* __linux__ */
-
-/* "wait" */
-extern void sx_77616974(environment *env)
-{
-  int dur;
-
-  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;
-  }
-
-  dur= CAR(env->head)->content.i;
-  toss(env);
-
-  usleep(dur);
+    return readstream(env, env->inputstream);
 }
 
 extern void copying(environment *env)
@@ -2131,272 +1350,85 @@
 POSSIBILITY OF SUCH DAMAGES.\n");
 }
 
-/* "*" */
-extern void sx_2a(environment *env)
-{
-  int a, b;
-  float fa, fb;
-
-  if(env->head->type==empty || CDR(env->head)->type==empty) {
-    printerr("Too Few Arguments");
-    env->err= 1;
-    return;
-  }
-  
-  if(CAR(env->head)->type==integer
-     && CAR(CDR(env->head))->type==integer) {
-    a= CAR(env->head)->content.i;
-    toss(env); if(env->err) return;
-    b= CAR(env->head)->content.i;
-    toss(env); if(env->err) return;
-    push_int(env, b*a);
-
-    return;
-  }
-
-  if(CAR(env->head)->type==tfloat
-     && CAR(CDR(env->head))->type==tfloat) {
-    fa= CAR(env->head)->content.f;
-    toss(env); if(env->err) return;
-    fb= CAR(env->head)->content.f;
-    toss(env); if(env->err) return;
-    push_float(env, fb*fa);
-    
-    return;
-  }
-
-  if(CAR(env->head)->type==tfloat
-     && CAR(CDR(env->head))->type==integer) {
-    fa= CAR(env->head)->content.f;
-    toss(env); if(env->err) return;
-    b= CAR(env->head)->content.i;
-    toss(env); if(env->err) return;
-    push_float(env, b*fa);
-    
-    return;
-  }
-
-  if(CAR(env->head)->type==integer
-     && CAR(CDR(env->head))->type==tfloat) {
-    a= CAR(env->head)->content.i;
-    toss(env); if(env->err) return;
-    fb= CAR(env->head)->content.f;
-    toss(env); if(env->err) return;
-    push_float(env, fb*a);
-
-    return;
-  }
-
-  printerr("Bad Argument Type");
-  env->err= 2;
-}
-
-/* "/" */
-extern void sx_2f(environment *env)
-{
-  int a, b;
-  float fa, fb;
-
-  if(env->head->type==empty || CDR(env->head)->type==empty) {
-    printerr("Too Few Arguments");
-    env->err= 1;
-    return;
-  }
-  
-  if(CAR(env->head)->type==integer
-     && CAR(CDR(env->head))->type==integer) {
-    a= CAR(env->head)->content.i;
-    toss(env); if(env->err) return;
-    b= CAR(env->head)->content.i;
-    toss(env); if(env->err) return;
-    push_float(env, b/a);
-
-    return;
-  }
-
-  if(CAR(env->head)->type==tfloat
-     && CAR(CDR(env->head))->type==tfloat) {
-    fa= CAR(env->head)->content.f;
-    toss(env); if(env->err) return;
-    fb= CAR(env->head)->content.f;
-    toss(env); if(env->err) return;
-    push_float(env, fb/fa);
-    
-    return;
-  }
-
-  if(CAR(env->head)->type==tfloat
-     && CAR(CDR(env->head))->type==integer) {
-    fa= CAR(env->head)->content.f;
-    toss(env); if(env->err) return;
-    b= CAR(env->head)->content.i;
-    toss(env); if(env->err) return;
-    push_float(env, b/fa);
-    
-    return;
-  }
-
-  if(CAR(env->head)->type==integer
-     && CAR(CDR(env->head))->type==tfloat) {
-    a= CAR(env->head)->content.i;
-    toss(env); if(env->err) return;
-    fb= CAR(env->head)->content.f;
-    toss(env); if(env->err) return;
-    push_float(env, fb/a);
-
-    return;
-  }
-
-  printerr("Bad Argument Type");
-  env->err= 2;
-}
-
-/* "mod" */
-extern void mod(environment *env)
+/* General assoc function */
+void assocgen(environment *env, funcp eqfunc)
 {
-  int a, b;
-
-  if(env->head->type==empty || CDR(env->head)->type==empty) {
-    printerr("Too Few Arguments");
-    env->err= 1;
-    return;
-  }
-  
-  if(CAR(env->head)->type==integer
-     && CAR(CDR(env->head))->type==integer) {
-    a= CAR(env->head)->content.i;
-    toss(env); if(env->err) return;
-    b= CAR(env->head)->content.i;
-    toss(env); if(env->err) return;
-    push_int(env, b%a);
-
-    return;
-  }
-
-  printerr("Bad Argument Type");
-  env->err= 2;
-}
+  value *key, *item;
 
-/* "div" */
-extern void sx_646976(environment *env)
-{
-  int a, b;
-  
+  /* 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==integer
-     && CAR(CDR(env->head))->type==integer) {
-    a= CAR(env->head)->content.i;
-    toss(env); if(env->err) return;
-    b= CAR(env->head)->content.i;
-    toss(env); if(env->err) return;
-    push_int(env, (int)b/a);
-
-    return;
-  }
-
-  printerr("Bad Argument Type");
-  env->err= 2;
-}
-
-extern void setcar(environment *env)
-{
-  if(env->head->type==empty || CDR(env->head)->type==empty) {
-    printerr("Too Few Arguments");
-    env->err= 1;
-    return;
-  }
-
-  if(CDR(env->head)->type!=tcons) {
+  if(CAR(env->head)->type!=tcons) {
     printerr("Bad Argument Type");
     env->err= 2;
     return;
   }
 
-  CAR(CAR(CDR(env->head)))=CAR(env->head);
-  toss(env);
-}
+  key=CAR(CDR(env->head));
+  item=CAR(env->head);
 
-extern void setcdr(environment *env)
-{
-  if(env->head->type==empty || CDR(env->head)->type==empty) {
-    printerr("Too Few Arguments");
-    env->err= 1;
+  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(CDR(env->head)->type!=tcons) {
-    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;
 
-  CDR(CAR(CDR(env->head)))=CAR(env->head);
-  toss(env);
-}
+    if(item->type!=tcons) {
+      printerr("Bad Argument Type");
+      env->err= 2;
+      return;
+    }
 
-extern void car(environment *env)
-{
-  if(env->head->type==empty) {
-    printerr("Too Few Arguments");
-    env->err= 1;
-    return;
+    item=CDR(item);
   }
 
-  if(CAR(env->head)->type!=tcons) {
-    printerr("Bad Argument Type");
-    env->err= 2;
-    return;
+  if(item->type == tcons){	/* A match was found */
+    push_val(env, CAR(item));
+  } else {
+    push_int(env, 0);
   }
-
-  CAR(env->head)=CAR(CAR(env->head));
+  swap(env); if(env->err) return;
+  toss(env); if(env->err) return;
+  swap(env); if(env->err) return;
+  toss(env);
 }
 
-extern void cdr(environment *env)
+/* Discard the top element of the stack. */
+extern void toss(environment *env)
 {
   if(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;
-  }
-
-  CAR(env->head)=CDR(CAR(env->head));
+  
+  env->head= CDR(env->head); /* Remove the top stack item */
 }
 
-extern void cons(environment *env)
-{
-  value *val;
-
-  if(env->head->type==empty || CDR(env->head)->type==empty) {
-    printerr("Too Few Arguments");
-    env->err= 1;
-    return;
-  }
-
-  val=new_val(env);
-  val->content.c= malloc(sizeof(pair));
-  assert(val->content.c!=NULL);
-
-  env->gc_count += sizeof(pair);
-  val->type=tcons;
-
-  CAR(val)= CAR(CDR(env->head));
-  CDR(val)= CAR(env->head);
-
-  push_val(env, val);
-
-  swap(env); if(env->err) return;
-  toss(env); if(env->err) return;
-  swap(env); if(env->err) return;
-  toss(env); if(env->err) return;
-}