--- stack/stack.c	2002/02/05 23:00:42	1.33
+++ stack/stack.c	2002/03/27 19:53:01	1.123
@@ -1,84 +1,98 @@
-/* printf */
+/* -*- coding: utf-8; -*- */
+/*
+    stack - an interactive interpreter for a stack-based language
+    Copyright (C) 2002	Mats Alritzson and Teddy Hogeborn
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program 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 General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+
+    Authors: Mats Alritzson <masse@fukt.bth.se>
+	     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_SUCCESS */
+/* 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>
 
-#define HASHTBLSIZE 65536
-
-/* First, define some types. */
+#ifdef __linux__
+/* mtrace, muntrace */
+#include <mcheck.h>
+/* ioctl */
+#include <sys/ioctl.h>
+/* KDMKTONE */
+#include <linux/kd.h>
+#endif /* __linux__ */
 
-/* A value of some type */
-typedef struct {
-  enum {
-    integer,
-    string,
-    ref,			/* Reference (to an element in the
-                                   hash table) */
-    func,			/* Function pointer */
-    symb, 
-    list
-  } type;			/* Type of stack element */
-
-  union {
-    void *ptr;			/* Pointer to the content */
-    int val;			/* ...or an integer */
-  } content;			/* Stores a pointer or an integer */
-
-  int refcount;			/* Reference counter */
-
-} value;
-
-/* A symbol with a name and possible value */
-/* (These do not need reference counters, they are kept unique by
-   hashing.) */
-typedef struct symbol_struct {
-  char *id;			/* Symbol name */
-  value *val;			/* The value (if any) bound to it */
-  struct symbol_struct *next;	/* In case of hashing conflicts, a */
-} symbol;			/* symbol is a kind of stack item. */
-
-/* A type for a hash table for symbols */
-typedef symbol *hashtbl[HASHTBLSIZE]; /* Hash table declaration */
-
-/* An item (value) on a stack */
-typedef struct stackitem_struct
-{
-  value *item;			/* The value on the stack */
-  struct stackitem_struct *next; /* Next item */
-} stackitem;
-
-/* An environment; gives access to the stack and a hash table of
-   defined symbols */
-typedef struct {
-  stackitem *head;		/* Head of the stack */
-  hashtbl symbols;		/* Hash table of all variable bindings */
-  int err;			/* Error flag */
-} environment;
-
-/* A type for pointers to external functions */
-typedef void (*funcp)(environment *); /* funcp is a pointer to a void
-					 function (environment *) */
+#include "stack.h"
 
 /* Initialize a newly created environment */
 void init_env(environment *env)
 {
-  long i;
+  int i;
+
+  env->gc_limit= 400000;
+  env->gc_count= 0;
+  env->gc_ref= NULL;
 
+  env->head= new_val(env);
   for(i= 0; i<HASHTBLSIZE; i++)
     env->symbols[i]= NULL;
+  env->err= 0;
+  env->in_string= NULL;
+  env->free_string= NULL;
+  env->inputstream= stdin;
+  env->interactive= 1;
+}
+
+void printerr(const char* in_string)
+{
+  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)
 {
-  long i= 0;
-  unsigned long out_hash= 0;
+  int i= 0;
+  unsigned int out_hash= 0;
   char key= '\0';
   symbol **position;
   
@@ -103,59 +117,284 @@
   }
 }
 
-/* Generic push function. */
-int push(stackitem** stack_head, stackitem* in_item)
+/* Create new value */
+value* new_val(environment *env)
+{
+  value *nval= malloc(sizeof(value));
+  stackitem *nitem= malloc(sizeof(stackitem));
+
+  assert(nval != NULL);
+  assert(nitem != NULL);
+
+  nval->content.ptr= NULL;
+  nval->type= empty;
+
+  nitem->item= nval;
+  nitem->next= env->gc_ref;
+
+  env->gc_ref= nitem;
+
+  env->gc_count += sizeof(value);
+  nval->gc.flag.mark= 0;
+  nval->gc.flag.protect= 0;
+
+  return nval;
+}
+
+/* Mark values recursively. 
+   Marked values are not collected by the GC. */
+inline void gc_mark(value *val)
+{
+  if(val==NULL || val->gc.flag.mark)
+    return;
+
+  val->gc.flag.mark= 1;
+
+  if(val->type==tcons) {
+    gc_mark(CAR(val));
+    gc_mark(CDR(val));
+  }
+}
+
+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)
+{
+  stackitem *new_head= NULL, *titem;
+  symbol *tsymb;
+  int i;
+
+  if(env->interactive)
+    printf("Garbage collecting.");
+
+  /* Mark values on stack */
+  gc_mark(env->head);
+
+  if(env->interactive)
+    printf(".");
+
+
+  /* Mark values in hashtable */
+  for(i= 0; i<HASHTBLSIZE; i++)
+    for(tsymb= env->symbols[i]; tsymb!=NULL; tsymb= tsymb->next)
+      if (tsymb->val != NULL)
+	gc_mark(tsymb->val);
+
+
+  if(env->interactive)
+    printf(".");
+
+  env->gc_count= 0;
+
+  while(env->gc_ref!=NULL) {	/* Sweep unused values */
+
+    if(!(env->gc_ref->item->gc.no_gc)){ /* neither mark nor protect */
+
+      /* Remove content */
+      switch(env->gc_ref->item->type){
+      case string:
+	free(env->gc_ref->item->content.ptr);
+	break;
+      case tcons:
+	free(env->gc_ref->item->content.c);
+	break;
+      case empty:
+      case integer:
+      case tfloat:
+      case func:
+      case symb:
+	/* Symbol strings are freed when walking the hash table */
+      }
+
+      free(env->gc_ref->item);	/* Remove from gc_ref */
+      titem= env->gc_ref->next;
+      free(env->gc_ref);	/* Remove value */
+      env->gc_ref= titem;
+      continue;
+    }
+#ifdef DEBUG
+    printf("Kept value (%p)", env->gc_ref->item);
+    if(env->gc_ref->item->gc.flag.mark)
+      printf(" (marked)");
+    if(env->gc_ref->item->gc.flag.protect)
+      printf(" (protected)");
+    switch(env->gc_ref->item->type){
+    case integer:
+      printf(" integer: %d", env->gc_ref->item->content.i);
+      break;
+    case func:
+      printf(" func: %p", env->gc_ref->item->content.ptr);
+      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);
+      break;
+    default:
+      printf(" <unknown %d>", (env->gc_ref->item->type));
+    }
+    printf("\n");
+#endif /* DEBUG */
+
+    /* 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;
+    
+    titem= env->gc_ref->next;
+    env->gc_ref->next= new_head;
+    new_head= env->gc_ref;
+    new_head->item->gc.flag.mark= 0;
+    env->gc_ref= titem;
+  }
+
+  if (env->gc_limit < env->gc_count*2)
+    env->gc_limit= env->gc_count*2;
+
+  env->gc_ref= new_head;
+
+  if(env->interactive)
+    printf("done (%d bytes still allocated)\n", env->gc_count);
+
+}
+
+/* Protect values from GC */
+void protect(value *val)
 {
-  in_item->next= *stack_head;
-  *stack_head= in_item;
-  return 1;
+  if(val==NULL || val->gc.flag.protect)
+    return;
+
+  val->gc.flag.protect= 1;
+
+  if(val->type==tcons) {
+    protect(CAR(val));
+    protect(CDR(val));
+  }
+}
+
+/* Unprotect values from GC */
+void unprotect(value *val)
+{
+  if(val==NULL || !(val->gc.flag.protect))
+    return;
+
+  val->gc.flag.protect= 0;
+
+  if(val->type==tcons) {
+    unprotect(CAR(val));
+    unprotect(CDR(val));
+  }
 }
 
 /* Push a value onto the stack */
-void push_val(stackitem **stack_head, value *val)
+void push_val(environment *env, value *val)
 {
-  stackitem *new_item= malloc(sizeof(stackitem));
-  new_item->item= val;
-  val->refcount++;
-  push(stack_head, new_item);
+  value *new_value= new_val(env);
+
+  new_value->content.c= malloc(sizeof(pair));
+  assert(new_value->content.c!=NULL);
+  env->gc_count += sizeof(pair);
+  new_value->type= tcons;
+  CAR(new_value)= val;
+  CDR(new_value)= env->head;
+  env->head= new_value;
 }
 
-/* Push an integer onto the stack. */
-int push_int(stackitem **stack_head, int in_val) 
+/* Push an integer onto the stack */
+void push_int(environment *env, int in_val) 
 {
-  value *new_value= malloc(sizeof(value));
-  stackitem *new_item= malloc(sizeof(stackitem));
-  new_item->item= new_value;
+  value *new_value= new_val(env);
   
-  new_value->content.val= in_val;
+  new_value->content.i= in_val;
   new_value->type= integer;
-  new_value->refcount=1;
 
-  push(stack_head, new_item);
-  return 1;
+  push_val(env, new_value);
+}
+
+/* Push a floating point number onto the stack */
+void push_float(environment *env, float in_val)
+{
+  value *new_value= new_val(env);
+
+  new_value->content.f= in_val;
+  new_value->type= tfloat;
+
+  push_val(env, new_value);
 }
 
 /* Copy a string onto the stack. */
-int push_cstring(stackitem **stack_head, const char *in_string)
+void push_cstring(environment *env, const char *in_string)
 {
-  value *new_value= malloc(sizeof(value));
-  stackitem *new_item= malloc(sizeof(stackitem));
-  new_item->item=new_value;
+  value *new_value= new_val(env);
+  int length= strlen(in_string)+1;
 
-  new_value->content.ptr= malloc(strlen(in_string)+1);
+  new_value->content.ptr= malloc(length);
+  assert(new_value != NULL);
+  env->gc_count += length;
   strcpy(new_value->content.ptr, in_string);
   new_value->type= string;
-  new_value->refcount=1;
 
-  push(stack_head, new_item);
-  return 1;
+  push_val(env, new_value);
+}
+
+/* Mangle a symbol name to a valid C identifier name */
+char *mangle_str(const char *old_string)
+{
+  char validchars[]= "0123456789abcdef";
+  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'){
+    current[0]= validchars[(unsigned char)(old_string[0])/16];
+    current[1]= validchars[(unsigned char)(old_string[0])%16];
+    current+= 2;
+    old_string++;
+  }
+  current[0]= '\0';
+
+  return new_string;		/* The caller must free() it */
+}
+
+extern void mangle(environment *env)
+{
+  char *new_string;
+
+  if(env->head->type==empty) {
+    printerr("Too Few Arguments");
+    env->err= 1;
+    return;
+  }
+
+  if(CAR(env->head)->type!=string) {
+    printerr("Bad Argument Type");
+    env->err= 2;
+    return;
+  }
+
+  new_string= 
+    mangle_str((const char *)(CAR(env->head)->content.ptr));
+
+  toss(env);
+  if(env->err) return;
+
+  push_cstring(env, new_string);
 }
 
 /* Push a symbol onto the stack. */
-int push_sym(environment *env, const char *in_string)
+void push_sym(environment *env, const char *in_string)
 {
-  stackitem *new_item;		/* The new stack item */
-  /* ...which will contain... */
   value *new_value;		/* A new symbol value */
   /* ...which might point to... */
   symbol **new_symbol;		/* (if needed) A new actual symbol */
@@ -165,15 +404,16 @@
   void *funcptr;		/* A function pointer */
 
   static void *handle= NULL;	/* Dynamic linker handle */
+  const char *dlerr;		/* Dynamic linker error */
+  char *mangled;		/* Mangled function name */
 
-  /* Create a new stack item containing a new value */
-  new_item= malloc(sizeof(stackitem));
-  new_value= malloc(sizeof(value));
-  new_item->item=new_value;
+  new_value= new_val(env);
+  protect(new_value);
+  new_fvalue= new_val(env);
+  protect(new_fvalue);
 
   /* The new value is a symbol */
   new_value->type= symb;
-  new_value->refcount= 1;
 
   /* Look up the symbol name in the hash table */
   new_symbol= hash(env->symbols, in_string);
@@ -183,9 +423,11 @@
 
     /* 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 */
@@ -196,157 +438,246 @@
     if(handle==NULL)		/* If no handle */
       handle= dlopen(NULL, RTLD_LAZY);
 
-    funcptr= dlsym(handle, in_string); /* Get function pointer */
-    if(dlerror()==NULL) { 	/* If a function was found */
-      new_fvalue= malloc(sizeof(value)); /* Create a new value */
-      new_fvalue->type=func;	/* The new value is a function pointer */
-      new_fvalue->content.ptr=funcptr; /* Store function pointer */
+    mangled= mangle_str(in_string); /* mangle the name */
+    funcptr= dlsym(handle, mangled); /* and try to find it */
+
+    dlerr= dlerror();
+    if(dlerr != NULL) {		/* If no function was found */
+      funcptr= dlsym(handle, in_string); /* Get function pointer */
+      dlerr= dlerror();
+    }
+
+    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_symbol)->val= new_fvalue; /* Bind the symbol to the new
                                          function value */
-      new_fvalue->refcount= 1;
     }
-  }
-  push(&(env->head), new_item);
-  return 1;
-}
 
-void printerr(const char* in_string) {
-  fprintf(stderr, "Err: %s\n", in_string);
-}
-
-/* Throw away a value */
-void free_val(value *val){
-  stackitem *item, *temp;
-
-  val->refcount--;		/* Decrease the reference count */
-  if(val->refcount == 0){
-    switch (val->type){		/* and free the contents if necessary */
-    case string:
-      free(val->content.ptr);
-    case list:			/* lists needs to be freed recursively */
-      item=val->content.ptr;
-      while(item != NULL) {	/* for all stack items */
-	free_val(item->item);	/* free the value */
-	temp=item->next;	/* save next ptr */
-	free(item);		/* free the stackitem */
-	item=temp;		/* go to next stackitem */
-      }
-      free(val);		/* Free the actual list value */
-      break;
-    default:
-      break;
-    }
+    free(mangled);
   }
-}
-
-/* Discard the top element of the stack. */
-extern void toss(environment *env)
-{
-  stackitem *temp= env->head;
 
-  if((env->head)==NULL) {
-    printerr("Stack empty");
-    return;
-  }
-  
-  free_val(env->head->item);	/* Free the value */
-  env->head= env->head->next;	/* Remove the top stack item */
-  free(temp);			/* Free the old top stack item */
+  push_val(env, new_value);
+  unprotect(new_value); unprotect(new_fvalue);
 }
 
 /* Print newline. */
-extern void nl(environment *env)
+extern void nl()
 {
   printf("\n");
 }
 
-/* Prints the top element of the stack. */
-void print_h(stackitem *stack_head)
+/* Gets the type of a value */
+extern void type(environment *env)
 {
-
-  if(stack_head==NULL) {
-    printerr("Stack empty");
+  if(env->head->type==empty) {
+    printerr("Too Few Arguments");
+    env->err= 1;
     return;
   }
 
-  switch(stack_head->item->type) {
+  switch(CAR(env->head)->type){
+  case empty:
+    push_sym(env, "empty");
+    break;
   case integer:
-    printf("%d", stack_head->item->content.val);
+    push_sym(env, "integer");
+    break;
+  case tfloat:
+    push_sym(env, "float");
     break;
   case string:
-    printf("\"%s\"", (char*)stack_head->item->content.ptr);
+    push_sym(env, "string");
     break;
   case symb:
-    printf("'%s'", ((symbol *)(stack_head->item->content.ptr))->id);
+    push_sym(env, "symbol");
     break;
-  default:
-    printf("%p", (funcp)(stack_head->item->content.ptr));
+  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, stackitem *stack)
+{
+  stackitem *titem, *tstack;
+  int depth;
+
+  switch(val->type) {
+  case empty:
+    printf("[]");
+    break;
+  case integer:
+    printf("%d", val->content.i);
+    break;
+  case tfloat:
+    printf("%f", val->content.f);
+    break;
+  case string:
+    if(noquote)
+      printf("%s", (char*)(val->content.ptr));
+    else
+      printf("\"%s\"", (char*)(val->content.ptr));
+    break;
+  case symb:
+    printf("%s", val->content.sym->id);
+    break;
+  case func:
+    printf("#<function %p>", (funcp)(val->content.ptr));
+    break;
+  case tcons:
+    printf("[ ");
+    tstack= stack;
+    do {
+      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, */
+	printf("#%d#", depth);	/* print a depth reference */
+      } else {
+	print_val(CAR(val), noquote, tstack);
+      }
+      val= CDR(val);
+      switch(val->type){
+      case empty:
+	break;
+      case tcons:
+	/* 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, */
+	  printf(" . #%d#", depth); /* print a depth reference */
+	} else {
+	  printf(" ");
+	}
+	break;
+      default:
+	printf(" . ");		/* Improper list */
+	print_val(val, noquote, tstack);
+      }
+    } while(val->type == tcons && titem == NULL);
+    titem=tstack;
+    while(titem != stack){
+      tstack=titem->next;
+      free(titem);
+      titem=tstack;
+    }
+    printf(" ]");
     break;
   }
 }
 
-extern void print_(environment *env) {
-  print_h(env->head);
+extern void print_(environment *env)
+{
+  if(env->head->type==empty) {
+    printerr("Too Few Arguments");
+    env->err= 1;
+    return;
+  }
+  print_val(CAR(env->head), 0, NULL);
+  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);
+}
+
+extern void princ_(environment *env)
+{
+  if(env->head->type==empty) {
+    printerr("Too Few Arguments");
+    env->err= 1;
+    return;
+  }
+  print_val(CAR(env->head), 1, NULL);
+}
+
+/* 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(stackitem *stack_head, long counter)
+void print_st(value *stack_head, long counter)
 { 
-  if(stack_head->next != NULL)
-    print_st(stack_head->next, counter+1);
+  if(CDR(stack_head)->type != empty)
+    print_st(CDR(stack_head), counter+1);
   printf("%ld: ", counter);
-  print_h(stack_head);
+  print_val(CAR(stack_head), 0, NULL);
   nl();
 }
 
-
-
 /* Prints the stack. */
 extern void printstack(environment *env)
 {
-  if(env->head != NULL) {
-    print_st(env->head, 1);
-    nl();
-  } else {
-    printerr("Stack empty");
+  if(env->head->type == empty) {
+    printf("Stack Empty\n");
+    return;
   }
+
+  print_st(env->head, 1);
 }
 
 /* Swap the two top elements on the stack. */
 extern void swap(environment *env)
 {
-  stackitem *temp= env->head;
+  value *temp= env->head;
   
-  if((env->head)==NULL) {
-    printerr("Stack empty");
+  if(env->head->type == empty || CDR(env->head)->type == empty) {
+    printerr("Too Few Arguments");
+    env->err=1;
     return;
   }
 
-  if(env->head->next==NULL) {
-    printerr("Not enough arguments");
-    return;
-  }
-
-  env->head= env->head->next;
-  temp->next= env->head->next;
-  env->head->next= temp;
+  env->head= CDR(env->head);
+  CDR(temp)= CDR(env->head);
+  CDR(env->head)= temp;
 } 
 
-stackitem* copy(stackitem* in_item)
+/* Rotate the first three elements on the stack. */
+extern void rot(environment *env)
 {
-  stackitem *out_item= malloc(sizeof(stackitem));
-
-  memcpy(out_item, in_item, sizeof(stackitem));
-  out_item->next= NULL;
-
-  return out_item;
+  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 */
@@ -354,22 +685,29 @@
 {
   value *val;
 
-  if(env->head == NULL) {
-    printerr("Stack empty");
+  if(env->head->type==empty) {
+    printerr("Too Few Arguments");
+    env->err= 1;
     return;
   }
 
-  if(env->head->item->type!=symb) {
-    printerr("Not a symbol");
+  if(CAR(env->head)->type!=symb) {
+    printerr("Bad Argument Type");
+    env->err= 2;
     return;
   }
-  val=((symbol *)(env->head->item->content.ptr))->val;
+
+  val= CAR(env->head)->content.sym->val;
   if(val == NULL){
-    printerr("Unbound variable");
+    printerr("Unbound Variable");
+    env->err= 3;
     return;
   }
-  toss(env);		/* toss the symbol */
-  push_val(&(env->head), val); /* Return its bound value */
+  push_val(env, val);		/* Return the symbol's bound value */
+  swap(env);
+  if(env->err) return;
+  toss(env);			/* toss the symbol */
+  if(env->err) return;
 }
 
 /* If the top element is a symbol, determine if it's bound to a
@@ -378,186 +716,184 @@
 extern void eval(environment *env)
 {
   funcp in_func;
-  value* val;
-  if(env->head==NULL) {
-    printerr("Stack empty");
+  value* temp_val;
+  value* iterator;
+
+ eval_start:
+
+  gc_maybe(env);
+
+  if(env->head->type==empty) {
+    printerr("Too Few Arguments");
+    env->err= 1;
     return;
   }
 
-  /* if it's a symbol */
-  if(env->head->item->type==symb) {
-
-    /* If it's not bound to anything */
-    if (((symbol *)(env->head->item->content.ptr))->val == NULL) {
-      printerr("Unbound variable");
-      return;
+  switch(CAR(env->head)->type) {
+    /* if it's a symbol */
+  case symb:
+    rcl(env);			/* get its contents */
+    if(env->err) return;
+    if(CAR(env->head)->type!=symb){ /* don't recurse symbols */
+      goto eval_start;
     }
+    return;
+
+    /* If it's a lone function value, run it */
+  case func:
+    in_func= (funcp)(CAR(env->head)->content.ptr);
+    toss(env); 
+    if(env->err) return;
+    return in_func(env);
+
+    /* If it's a list */
+  case tcons:
+    temp_val= CAR(env->head);
+    protect(temp_val);
+
+    toss(env); if(env->err) return;
+    iterator= temp_val;
     
-    /* If it contains a function */
-    if (((symbol *)(env->head->item->content.ptr))->val->type == func) {
-      in_func=
-	(funcp)(((symbol *)(env->head->item->content.ptr))->val->content.ptr);
-      toss(env);
-      (*in_func)(env);		/* Run the function */
-      return;
-    } else {			/* If it's not a function */
-      val=((symbol *)(env->head->item->content.ptr))->val;
-      toss(env);		/* toss the symbol */
-      push_val(&(env->head), val); /* Return its bound value */
+    while(iterator->type != empty) {
+      push_val(env, CAR(iterator));
+      
+      if(CAR(env->head)->type==symb
+	 && CAR(env->head)->content.sym->id[0]==';') {
+	toss(env);
+	if(env->err) return;
+	
+	if(CDR(iterator)->type == empty){
+	  goto eval_start;
+	}
+	eval(env);
+	if(env->err) return;
+      }
+      if (CDR(iterator)->type == empty || CDR(iterator)->type == tcons) 
+	iterator= CDR(iterator);
+      else {
+	printerr("Bad Argument Type"); /* Improper list */
+	env->err= 2;
+	return;
+      }
     }
+    unprotect(temp_val);
+    return;
+
+  case empty:
+  case integer:
+  case tfloat:
+  case string:
+    return;
   }
+}
 
-  /* If it's a lone function value, run it */
-  if(env->head->item->type==func) {
-    in_func= (funcp)(env->head->item->content.ptr);
-    toss(env); 
-    (*in_func)(env);
+/* 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);
+  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)
 {
-  void* delimiter;
-  stackitem *iterator, *temp;
-  value *pack;
+  value *iterator, *temp, *ending;
 
-  delimiter= env->head->item->content.ptr; /* Get delimiter */
-  toss(env);
+  ending=new_val(env);
 
   iterator= env->head;
-
-  if(iterator==NULL || iterator->item->content.ptr==delimiter) {
-    temp= NULL;
+  if(iterator->type == empty
+     || (CAR(iterator)->type==symb
+     && CAR(iterator)->content.sym->id[0]=='[')) {
+    temp= ending;
     toss(env);
   } else {
     /* Search for first delimiter */
-    while(iterator->next!=NULL
-	  && iterator->next->item->content.ptr!=delimiter)
-      iterator= iterator->next;
+    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= iterator->next;
-    iterator->next= NULL;
-    
-    if(env->head!=NULL)
+    env->head= CDR(iterator);
+    CDR(iterator)= ending;
+
+    if(env->head->type != empty)
       toss(env);
   }
 
   /* Push list */
-  pack= malloc(sizeof(value));
-  pack->type= list;
-  pack->content.ptr= temp;
-  pack->refcount= 1;
-
-  temp= malloc(sizeof(stackitem));
-  temp->item= pack;
-
-  push(&(env->head), temp);
-}
-
-/* Parse input. */
-int stack_read(environment *env, char *in_line) 
-{
-  char *temp, *rest;
-  int itemp;
-  size_t inlength= strlen(in_line)+1;
-  int convert= 0;
-  static int non_eval_flag= 0;
-
-  temp= malloc(inlength);
-  rest= malloc(inlength);
-
-  do {
-    /* If string */
-    if((convert= sscanf(in_line, "\"%[^\"\n\r]\" %[^\n\r]", temp, rest))) {
-      push_cstring(&(env->head), temp);
-      break;
-    }
-    /* If integer */
-    if((convert= sscanf(in_line, "%d %[^\n\r]", &itemp, rest))) {
-      push_int(&(env->head), itemp);
-      break;
-    }
-    /* Escape ';' with '\' */
-    if((convert= sscanf(in_line, "\\%c%[^\n\r]", temp, rest))) {
-      temp[1]= '\0';
-      push_sym(env, temp);
-      break;
-    } 
-    /* If symbol */
-    if((convert= sscanf(in_line, "%[^][ ;\n\r_]%[^\n\r]", temp, rest))) {
-	push_sym(env, temp);
-	break;
-    }
-    /* If single char */
-    if((convert= sscanf(in_line, "%c%[^\n\r]", temp, rest))) {
-      if(*temp==';') {
-	if(!non_eval_flag) {
-	  eval(env);		/* Evaluate top element */
-	  break;
-	}
-	
-	push_sym(env, ";");
-	break;
-      }
-
-      if(*temp==']') {
-	push_sym(env, "[");
-	pack(env);
-	if(non_eval_flag!=0)
-	  non_eval_flag--;
-	break;
-      }
-
-      if(*temp=='[') {
-	push_sym(env, "[");
-	non_eval_flag++;
-	break;
-      }
-    }
-  } while(0);
-
 
-  free(temp);
-
-  if(convert<2) {
-    free(rest);
-    return 0;
-  }
-   
-  stack_read(env, rest);
-  
-  free(rest);
-  return 1;
+  push_val(env, temp);
+  rev(env);
 }
 
 /* Relocate elements of the list on the stack. */
 extern void expand(environment *env)
 {
-  stackitem *temp, *new_head;
+  value *temp, *new_head;
 
   /* Is top element a list? */
-  if(env->head==NULL || env->head->item->type!=list) {
-    printerr("Stack empty or not 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= env->head->item->content.ptr;
+  new_head= temp= CAR(env->head);
 
-  env->head->item->refcount++;
   toss(env);
 
   /* Find the end of the list */
-  while(temp->next!=NULL)
-    temp= temp->next;
+  while(CDR(temp)->type != empty) {
+    if (CDR(temp)->type == tcons)
+      temp= CDR(temp);
+    else {
+      printerr("Bad Argument Type"); /* Improper list */
+      env->err= 2;
+      return;
+    }
+  }
 
   /* Connect the tail of the list with the old stack head */
-  temp->next= env->head;
+  CDR(temp)= env->head;
   env->head= new_head;		/* ...and voila! */
 
 }
@@ -566,20 +902,18 @@
 extern void eq(environment *env)
 {
   void *left, *right;
-  int result;
 
-  if((env->head)==NULL || env->head->next==NULL) {
-    printerr("Not enough elements to compare");
+  if(env->head->type==empty || CDR(env->head)->type==empty) {
+    printerr("Too Few Arguments");
+    env->err= 1;
     return;
   }
 
-  left= env->head->item->content.ptr;
-  swap(env);
-  right= env->head->item->content.ptr;
-  result= (left==right);
-  
+  left= CAR(env->head)->content.ptr;
+  right= CAR(CDR(env->head))->content.ptr;
   toss(env); toss(env);
-  push_int(&(env->head), result);
+
+  push_int(env, left==right);
 }
 
 /* Negates the top element on the stack. */
@@ -587,14 +921,21 @@
 {
   int val;
 
-  if((env->head)==NULL || env->head->item->type!=integer) {
-    printerr("Stack empty or element is not a integer");
+  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= env->head->item->content.val;
+  val= CAR(env->head)->content.i;
   toss(env);
-  push_int(&(env->head), !val);
+  push_int(env, !val);
 }
 
 /* Compares the two top elements on the stack and return 0 if they're the
@@ -611,22 +952,23 @@
   symbol *sym;
 
   /* Needs two values on the stack, the top one must be a symbol */
-  if(env->head==NULL || env->head->next==NULL 
-     || env->head->item->type!=symb) {
-    printerr("Define what?");
+  if(env->head->type==empty || CDR(env->head)->type==empty) {
+    printerr("Too Few Arguments");
+    env->err= 1;
     return;
   }
 
-  /* long names are a pain */
-  sym=env->head->item->content.ptr;
+  if(CAR(env->head)->type!=symb) {
+    printerr("Bad Argument Type");
+    env->err= 2;
+    return;
+  }
 
-  /* if the symbol was bound to something else, throw it away */
-  if(sym->val != NULL)
-    free_val(sym->val);
+  /* long names are a pain */
+  sym= CAR(env->head)->content.ptr;
 
   /* Bind the symbol to the value */
-  sym->val= env->head->next->item;
-  sym->val->refcount++;		/* Increase the reference counter */
+  sym->val= CAR(CDR(env->head));
 
   toss(env); toss(env);
 } 
@@ -634,13 +976,37 @@
 /* Quit stack. */
 extern void quit(environment *env)
 {
+  int i;
+
+  clear(env);
+
+  if (env->err) return;
+  for(i= 0; i<HASHTBLSIZE; i++) {
+    while(env->symbols[i]!= NULL) {
+      forget_sym(&(env->symbols[i]));
+    }
+    env->symbols[i]= NULL;
+  }
+
+  env->gc_limit= 0;
+  gc_maybe(env);
+
+  words(env);
+
+  if(env->free_string!=NULL)
+    free(env->free_string);
+  
+#ifdef __linux__
+  muntrace();
+#endif
+
   exit(EXIT_SUCCESS);
 }
 
 /* Clear stack */
 extern void clear(environment *env)
 {
-  while(env->head!=NULL)
+  while(env->head->type != empty)
     toss(env);
 }
 
@@ -653,25 +1019,1516 @@
   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;
     }
   }
 }
 
-int main()
+/* Internal forget function */
+void forget_sym(symbol **hash_entry)
+{
+  symbol *temp;
+
+  temp= *hash_entry;
+  *hash_entry= (*hash_entry)->next;
+  
+  free(temp->id);
+  free(temp);
+}
+
+/* Forgets a symbol (remove it from the hash table) */
+extern void forget(environment *env)
+{
+  char* sym_id;
+
+  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;
+    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);
+}
+
+int main(int argc, char **argv)
 {
   environment myenv;
-  char in_string[100];
+
+  int c;			/* getopt option character */
+
+#ifdef __linux__
+  mtrace();
+#endif
 
   init_env(&myenv);
 
-  printf("okidok\n ");
+  myenv.interactive = isatty(STDIN_FILENO) && isatty(STDOUT_FILENO);
+
+  while ((c = getopt (argc, argv, "i")) != -1)
+    switch (c)
+      {
+      case 'i':
+	myenv.interactive = 1;
+	break;
+      case '?':
+	fprintf (stderr,
+		 "Unknown option character '\\x%x'.\n",
+		 optopt);
+	return EX_USAGE;
+      default:
+	abort ();
+      }
+  
+  if (optind < argc) {
+    myenv.interactive = 0;
+    myenv.inputstream= fopen(argv[optind], "r");
+    if(myenv.inputstream== NULL) {
+      perror(argv[0]);
+      exit (EX_NOINPUT);
+    }
+  }
 
-  while(fgets(in_string, 100, stdin) != NULL) {
-    stack_read(&myenv, in_string);
-    printf("okidok\n ");
+  if(myenv.interactive) {
+    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\
+under certain conditions; type 'copying;' for details.\n");
   }
 
-  exit(EXIT_SUCCESS);
+  while(1) {
+    if(myenv.in_string==NULL) {
+      if (myenv.interactive) {
+	if(myenv.err) {
+	  printf("(error %d)\n", myenv.err);
+	}
+	nl();
+	printstack(&myenv);
+	printf("> ");
+      }
+      myenv.err=0;
+    }
+    sx_72656164(&myenv);	/* "read" */
+    if (myenv.err==4) {		/* EOF */
+      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 */
+      eval(&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);
+    assert(new_string != NULL);
+    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)
+{
+  value *new_value;
+
+  if(old_value==NULL)
+    return NULL;
+
+  protect(old_value);
+  new_value= new_val(env);
+  new_value->type= old_value->type;
+
+  switch(old_value->type){
+  case tfloat:
+  case integer:
+  case func:
+  case symb:
+  case empty:
+    new_value->content= old_value->content;
+    break;
+  case string:
+    (char *)(new_value->content.ptr)= 
+      strdup((char *)(old_value->content.ptr));
+    break;
+  case tcons:
+
+    new_value->content.c= malloc(sizeof(pair));
+    assert(new_value->content.c!=NULL);
+    env->gc_count += sizeof(pair);
+
+    CAR(new_value)= copy_val(env, CAR(old_value)); /* recurse */
+    CDR(new_value)= copy_val(env, CDR(old_value)); /* recurse */
+    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)
+{
+  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;
+
+  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);
+    }
+  
+  } while(truth);
+
+  unprotect(loop); unprotect(test);
+}
+
+
+/* "for"; for-loop */
+extern void sx_666f72(environment *env)
+{
+  value *loop;
+  int foo1, foo2;
+
+  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!=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(CDR(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->type!=empty) {
+    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;
+    }
+  }
+  unprotect(loop); unprotect(foo);
+}
+
+/* "to" */
+extern void to(environment *env)
+{
+  int ending, start, i;
+  value *iterator, *temp, *end;
+
+  end= new_val(env);
+
+  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, "[");
+
+  if(ending>=start) {
+    for(i= ending; i>=start; i--)
+      push_int(env, i);
+  } else {
+    for(i= ending; i<=start; i++)
+      push_int(env, i);
+  }
+
+  iterator= env->head;
+
+  if(iterator->type==empty
+     || (CAR(iterator)->type==symb
+	 && CAR(iterator)->content.sym->id[0]=='[')) {
+    temp= end;
+    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)= end;
+
+    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);
+}
+
+/* "read"; Read a value and place on stack */
+extern void sx_72656164(environment *env)
+{
+  const char symbform[]= "%[a-zA-Z0-9!$%*+./:<=>?@^_~-]%n";
+  const char strform[]= "\"%[^\"]\"%n";
+  const char intform[]= "%i%n";
+  const char fltform[]= "%f%n";
+  const char blankform[]= "%*[ \t]%n";
+  const char ebrackform[]= "]%n";
+  const char semicform[]= ";%n";
+  const char bbrackform[]= "[%n";
+
+  int itemp, readlength= -1;
+  int count= -1;
+  float ftemp;
+  static int depth= 0;
+  char *match;
+  size_t inlength;
+
+  if(env->in_string==NULL) {
+    if(depth > 0 && env->interactive) {
+      printf("]> ");
+    }
+    readline(env); if(env->err) return;
+
+    if(((char *)(CAR(env->head)->content.ptr))[0]=='\0'){
+      env->err= 4;		/* "" means EOF */
+      return;
+    }
+    
+    env->in_string= malloc(strlen(CAR(env->head)->content.ptr)+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);
+    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) {
+    ; 
+  } else if(sscanf(env->in_string, fltform, &ftemp, &readlength) != EOF
+	    && readlength != -1) {
+    if(sscanf(env->in_string, intform, &itemp, &count) != EOF
+       && count==readlength) {
+      push_int(env, itemp);
+    } else {
+      push_float(env, ftemp);
+    }
+  } else if(sscanf(env->in_string, "\"\"%n", &readlength) != EOF
+	    && readlength != -1) {
+    push_cstring(env, "");
+  } else if(sscanf(env->in_string, strform, match, &readlength) != EOF
+	    && readlength != -1) {
+    push_cstring(env, match);
+  } else if(sscanf(env->in_string, symbform, match, &readlength) != EOF
+	    && readlength != -1) {
+    push_sym(env, match);
+  } else if(sscanf(env->in_string, ebrackform, &readlength) != EOF
+	    && readlength != -1) {
+    pack(env); if(env->err) return;
+    if(depth != 0) depth--;
+  } else if(sscanf(env->in_string, semicform, &readlength) != EOF
+	    && readlength != -1) {
+    push_sym(env, ";");
+  } else if(sscanf(env->in_string, bbrackform, &readlength) != EOF
+	    && readlength != -1) {
+    push_sym(env, "[");
+    depth++;
+  } else {
+    free(env->free_string);
+    env->in_string = env->free_string = NULL;
+  }
+  if (env->in_string != NULL) {
+    env->in_string += readlength;
+  }
+
+  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);
+}
+
+extern void copying(environment *env)
+{
+  printf("		    GNU GENERAL PUBLIC LICENSE\n\
+		       Version 2, June 1991\n\
+\n\
+ Copyright (C) 1989, 1991 Free Software Foundation, Inc.\n\
+     59 Temple Place, Suite 330, Boston, MA  02111-1307  USA\n\
+ Everyone is permitted to copy and distribute verbatim copies\n\
+ of this license document, but changing it is not allowed.\n\
+\n\
+			    Preamble\n\
+\n\
+  The licenses for most software are designed to take away your\n\
+freedom to share and change it.  By contrast, the GNU General Public\n\
+License is intended to guarantee your freedom to share and change free\n\
+software--to make sure the software is free for all its users.  This\n\
+General Public License applies to most of the Free Software\n\
+Foundation's software and to any other program whose authors commit to\n\
+using it.  (Some other Free Software Foundation software is covered by\n\
+the GNU Library General Public License instead.)  You can apply it to\n\
+your programs, too.\n\
+\n\
+  When we speak of free software, we are referring to freedom, not\n\
+price.  Our General Public Licenses are designed to make sure that you\n\
+have the freedom to distribute copies of free software (and charge for\n\
+this service if you wish), that you receive source code or can get it\n\
+if you want it, that you can change the software or use pieces of it\n\
+in new free programs; and that you know you can do these things.\n\
+\n\
+  To protect your rights, we need to make restrictions that forbid\n\
+anyone to deny you these rights or to ask you to surrender the rights.\n\
+These restrictions translate to certain responsibilities for you if you\n\
+distribute copies of the software, or if you modify it.\n\
+\n\
+  For example, if you distribute copies of such a program, whether\n\
+gratis or for a fee, you must give the recipients all the rights that\n\
+you have.  You must make sure that they, too, receive or can get the\n\
+source code.  And you must show them these terms so they know their\n\
+rights.\n\
+\n\
+  We protect your rights with two steps: (1) copyright the software, and\n\
+(2) offer you this license which gives you legal permission to copy,\n\
+distribute and/or modify the software.\n\
+\n\
+  Also, for each author's protection and ours, we want to make certain\n\
+that everyone understands that there is no warranty for this free\n\
+software.  If the software is modified by someone else and passed on, we\n\
+want its recipients to know that what they have is not the original, so\n\
+that any problems introduced by others will not reflect on the original\n\
+authors' reputations.\n\
+\n\
+  Finally, any free program is threatened constantly by software\n\
+patents.  We wish to avoid the danger that redistributors of a free\n\
+program will individually obtain patent licenses, in effect making the\n\
+program proprietary.  To prevent this, we have made it clear that any\n\
+patent must be licensed for everyone's free use or not licensed at all.\n\
+\n\
+  The precise terms and conditions for copying, distribution and\n\
+modification follow.\n\
+\n\
+		    GNU GENERAL PUBLIC LICENSE\n\
+   TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION\n\
+\n\
+  0. This License applies to any program or other work which contains\n\
+a notice placed by the copyright holder saying it may be distributed\n\
+under the terms of this General Public License.  The \"Program\", below,\n\
+refers to any such program or work, and a \"work based on the Program\"\n\
+means either the Program or any derivative work under copyright law:\n\
+that is to say, a work containing the Program or a portion of it,\n\
+either verbatim or with modifications and/or translated into another\n\
+language.  (Hereinafter, translation is included without limitation in\n\
+the term \"modification\".)  Each licensee is addressed as \"you\".\n\
+\n\
+Activities other than copying, distribution and modification are not\n\
+covered by this License; they are outside its scope.  The act of\n\
+running the Program is not restricted, and the output from the Program\n\
+is covered only if its contents constitute a work based on the\n\
+Program (independent of having been made by running the Program).\n\
+Whether that is true depends on what the Program does.\n\
+\n\
+  1. You may copy and distribute verbatim copies of the Program's\n\
+source code as you receive it, in any medium, provided that you\n\
+conspicuously and appropriately publish on each copy an appropriate\n\
+copyright notice and disclaimer of warranty; keep intact all the\n\
+notices that refer to this License and to the absence of any warranty;\n\
+and give any other recipients of the Program a copy of this License\n\
+along with the Program.\n\
+\n\
+You may charge a fee for the physical act of transferring a copy, and\n\
+you may at your option offer warranty protection in exchange for a fee.\n\
+\n\
+  2. You may modify your copy or copies of the Program or any portion\n\
+of it, thus forming a work based on the Program, and copy and\n\
+distribute such modifications or work under the terms of Section 1\n\
+above, provided that you also meet all of these conditions:\n\
+\n\
+    a) You must cause the modified files to carry prominent notices\n\
+    stating that you changed the files and the date of any change.\n\
+\n\
+    b) You must cause any work that you distribute or publish, that in\n\
+    whole or in part contains or is derived from the Program or any\n\
+    part thereof, to be licensed as a whole at no charge to all third\n\
+    parties under the terms of this License.\n\
+\n\
+    c) If the modified program normally reads commands interactively\n\
+    when run, you must cause it, when started running for such\n\
+    interactive use in the most ordinary way, to print or display an\n\
+    announcement including an appropriate copyright notice and a\n\
+    notice that there is no warranty (or else, saying that you provide\n\
+    a warranty) and that users may redistribute the program under\n\
+    these conditions, and telling the user how to view a copy of this\n\
+    License.  (Exception: if the Program itself is interactive but\n\
+    does not normally print such an announcement, your work based on\n\
+    the Program is not required to print an announcement.)\n\
+\n\
+These requirements apply to the modified work as a whole.  If\n\
+identifiable sections of that work are not derived from the Program,\n\
+and can be reasonably considered independent and separate works in\n\
+themselves, then this License, and its terms, do not apply to those\n\
+sections when you distribute them as separate works.  But when you\n\
+distribute the same sections as part of a whole which is a work based\n\
+on the Program, the distribution of the whole must be on the terms of\n\
+this License, whose permissions for other licensees extend to the\n\
+entire whole, and thus to each and every part regardless of who wrote it.\n\
+\n\
+Thus, it is not the intent of this section to claim rights or contest\n\
+your rights to work written entirely by you; rather, the intent is to\n\
+exercise the right to control the distribution of derivative or\n\
+collective works based on the Program.\n\
+\n\
+In addition, mere aggregation of another work not based on the Program\n\
+with the Program (or with a work based on the Program) on a volume of\n\
+a storage or distribution medium does not bring the other work under\n\
+the scope of this License.\n\
+\n\
+  3. You may copy and distribute the Program (or a work based on it,\n\
+under Section 2) in object code or executable form under the terms of\n\
+Sections 1 and 2 above provided that you also do one of the following:\n\
+\n\
+    a) Accompany it with the complete corresponding machine-readable\n\
+    source code, which must be distributed under the terms of Sections\n\
+    1 and 2 above on a medium customarily used for software interchange; or,\n\
+\n\
+    b) Accompany it with a written offer, valid for at least three\n\
+    years, to give any third party, for a charge no more than your\n\
+    cost of physically performing source distribution, a complete\n\
+    machine-readable copy of the corresponding source code, to be\n\
+    distributed under the terms of Sections 1 and 2 above on a medium\n\
+    customarily used for software interchange; or,\n\
+\n\
+    c) Accompany it with the information you received as to the offer\n\
+    to distribute corresponding source code.  (This alternative is\n\
+    allowed only for noncommercial distribution and only if you\n\
+    received the program in object code or executable form with such\n\
+    an offer, in accord with Subsection b above.)\n\
+\n\
+The source code for a work means the preferred form of the work for\n\
+making modifications to it.  For an executable work, complete source\n\
+code means all the source code for all modules it contains, plus any\n\
+associated interface definition files, plus the scripts used to\n\
+control compilation and installation of the executable.  However, as a\n\
+special exception, the source code distributed need not include\n\
+anything that is normally distributed (in either source or binary\n\
+form) with the major components (compiler, kernel, and so on) of the\n\
+operating system on which the executable runs, unless that component\n\
+itself accompanies the executable.\n\
+\n\
+If distribution of executable or object code is made by offering\n\
+access to copy from a designated place, then offering equivalent\n\
+access to copy the source code from the same place counts as\n\
+distribution of the source code, even though third parties are not\n\
+compelled to copy the source along with the object code.\n\
+\n\
+  4. You may not copy, modify, sublicense, or distribute the Program\n\
+except as expressly provided under this License.  Any attempt\n\
+otherwise to copy, modify, sublicense or distribute the Program is\n\
+void, and will automatically terminate your rights under this License.\n\
+However, parties who have received copies, or rights, from you under\n\
+this License will not have their licenses terminated so long as such\n\
+parties remain in full compliance.\n\
+\n\
+  5. You are not required to accept this License, since you have not\n\
+signed it.  However, nothing else grants you permission to modify or\n\
+distribute the Program or its derivative works.  These actions are\n\
+prohibited by law if you do not accept this License.  Therefore, by\n\
+modifying or distributing the Program (or any work based on the\n\
+Program), you indicate your acceptance of this License to do so, and\n\
+all its terms and conditions for copying, distributing or modifying\n\
+the Program or works based on it.\n\
+\n\
+  6. Each time you redistribute the Program (or any work based on the\n\
+Program), the recipient automatically receives a license from the\n\
+original licensor to copy, distribute or modify the Program subject to\n\
+these terms and conditions.  You may not impose any further\n\
+restrictions on the recipients' exercise of the rights granted herein.\n\
+You are not responsible for enforcing compliance by third parties to\n\
+this License.\n\
+\n\
+  7. If, as a consequence of a court judgment or allegation of patent\n\
+infringement or for any other reason (not limited to patent issues),\n\
+conditions are imposed on you (whether by court order, agreement or\n\
+otherwise) that contradict the conditions of this License, they do not\n\
+excuse you from the conditions of this License.  If you cannot\n\
+distribute so as to satisfy simultaneously your obligations under this\n\
+License and any other pertinent obligations, then as a consequence you\n\
+may not distribute the Program at all.  For example, if a patent\n\
+license would not permit royalty-free redistribution of the Program by\n\
+all those who receive copies directly or indirectly through you, then\n\
+the only way you could satisfy both it and this License would be to\n\
+refrain entirely from distribution of the Program.\n\
+\n\
+If any portion of this section is held invalid or unenforceable under\n\
+any particular circumstance, the balance of the section is intended to\n\
+apply and the section as a whole is intended to apply in other\n\
+circumstances.\n\
+\n\
+It is not the purpose of this section to induce you to infringe any\n\
+patents or other property right claims or to contest validity of any\n\
+such claims; this section has the sole purpose of protecting the\n\
+integrity of the free software distribution system, which is\n\
+implemented by public license practices.  Many people have made\n\
+generous contributions to the wide range of software distributed\n\
+through that system in reliance on consistent application of that\n\
+system; it is up to the author/donor to decide if he or she is willing\n\
+to distribute software through any other system and a licensee cannot\n\
+impose that choice.\n\
+\n\
+This section is intended to make thoroughly clear what is believed to\n\
+be a consequence of the rest of this License.\n\
+\n\
+  8. If the distribution and/or use of the Program is restricted in\n\
+certain countries either by patents or by copyrighted interfaces, the\n\
+original copyright holder who places the Program under this License\n\
+may add an explicit geographical distribution limitation excluding\n\
+those countries, so that distribution is permitted only in or among\n\
+countries not thus excluded.  In such case, this License incorporates\n\
+the limitation as if written in the body of this License.\n\
+\n\
+  9. The Free Software Foundation may publish revised and/or new versions\n\
+of the General Public License from time to time.  Such new versions will\n\
+be similar in spirit to the present version, but may differ in detail to\n\
+address new problems or concerns.\n\
+\n\
+Each version is given a distinguishing version number.  If the Program\n\
+specifies a version number of this License which applies to it and \"any\n\
+later version\", you have the option of following the terms and conditions\n\
+either of that version or of any later version published by the Free\n\
+Software Foundation.  If the Program does not specify a version number of\n\
+this License, you may choose any version ever published by the Free Software\n\
+Foundation.\n\
+\n\
+  10. If you wish to incorporate parts of the Program into other free\n\
+programs whose distribution conditions are different, write to the author\n\
+to ask for permission.  For software which is copyrighted by the Free\n\
+Software Foundation, write to the Free Software Foundation; we sometimes\n\
+make exceptions for this.  Our decision will be guided by the two goals\n\
+of preserving the free status of all derivatives of our free software and\n\
+of promoting the sharing and reuse of software generally.\n");
+}
+
+extern void warranty(environment *env)
+{
+  printf("			    NO WARRANTY\n\
+\n\
+  11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY\n\
+FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW.  EXCEPT WHEN\n\
+OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES\n\
+PROVIDE THE PROGRAM \"AS IS\" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED\n\
+OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF\n\
+MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  THE ENTIRE RISK AS\n\
+TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU.  SHOULD THE\n\
+PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING,\n\
+REPAIR OR CORRECTION.\n\
+\n\
+  12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING\n\
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR\n\
+REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES,\n\
+INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING\n\
+OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED\n\
+TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY\n\
+YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER\n\
+PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE\n\
+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)
+{
+  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;
+}
+
+/* "div" */
+extern void sx_646976(environment *env)
+{
+  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, (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) {
+    printerr("Bad Argument Type");
+    env->err= 2;
+    return;
+  }
+
+  CAR(CAR(CDR(env->head)))=CAR(env->head);
+  toss(env);
+}
+
+extern void setcdr(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) {
+    printerr("Bad Argument Type");
+    env->err= 2;
+    return;
+  }
+
+  CDR(CAR(CDR(env->head)))=CAR(env->head);
+  toss(env);
+}
+
+extern void car(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)=CAR(CAR(env->head));
+}
+
+extern void cdr(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));
+}
+
+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;
+}
+
+/*  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);
 }