--- stack/stack.c	2002/02/06 11:39:20	1.39
+++ stack/stack.c	2002/02/12 23:59:05	1.74
@@ -1,15 +1,15 @@
-/* printf */
+/* printf, sscanf, fgets, fprintf */
 #include <stdio.h>
-/* EXIT_SUCCESS */
+/* exit, EXIT_SUCCESS, malloc, free */
 #include <stdlib.h>
 /* NULL */
 #include <stddef.h>
 /* dlopen, dlsym, dlerror */
 #include <dlfcn.h>
-/* assert */
-#include <assert.h>
+/* strcmp, strcpy, strlen, strcat, strdup */
+#include <string.h>
 
-#define HASHTBLSIZE 65536
+#define HASHTBLSIZE 2048
 
 /* First, define some types. */
 
@@ -48,6 +48,7 @@
 typedef struct stackitem_struct
 {
   value *item;			/* The value on the stack */
+				/* (This is never NULL) */
   struct stackitem_struct *next; /* Next item */
 } stackitem;
 
@@ -57,6 +58,8 @@
   stackitem *head;		/* Head of the stack */
   hashtbl symbols;		/* Hash table of all variable bindings */
   int err;			/* Error flag */
+  int non_eval_flag;
+  char *in_string;		/* Input pending to be read */
 } environment;
 
 /* A type for pointers to external functions */
@@ -66,18 +69,68 @@
 /* Initialize a newly created environment */
 void init_env(environment *env)
 {
-  long i;
+  int i;
 
-  env->err=0;
+  env->in_string= NULL;
+  env->err= 0;
+  env->non_eval_flag= 0;
   for(i= 0; i<HASHTBLSIZE; i++)
     env->symbols[i]= NULL;
 }
 
+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);
+      break;
+    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;
+    case integer:
+    case func:
+    case symb:
+      break;
+    }
+  }
+}
+
+/* Discard the top element of the stack. */
+extern void toss(environment *env)
+{
+  stackitem *temp= env->head;
+
+  if((env->head)==NULL) {
+    printerr("Too Few Arguments");
+    env->err=1;
+    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 */
+}
+
 /* 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;
   
@@ -103,23 +156,23 @@
 }
 
 /* Generic push function. */
-void push(stackitem** stack_head, stackitem* in_item)
+void push(environment *env, stackitem* in_item)
 {
-  in_item->next= *stack_head;
-  *stack_head= in_item;
+  in_item->next= env->head;
+  env->head= in_item;
 }
 
 /* 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);
+  push(env, new_item);
 }
 
 /* Push an integer onto the stack. */
-void push_int(stackitem **stack_head, int in_val) 
+void push_int(environment *env, int in_val) 
 {
   value *new_value= malloc(sizeof(value));
   stackitem *new_item= malloc(sizeof(stackitem));
@@ -129,11 +182,11 @@
   new_value->type= integer;
   new_value->refcount=1;
 
-  push(stack_head, new_item);
+  push(env, new_item);
 }
 
 /* Copy a string onto the stack. */
-void 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));
@@ -144,7 +197,56 @@
   new_value->type= string;
   new_value->refcount=1;
 
-  push(stack_head, new_item);
+  push(env, new_item);
+}
+
+/* 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);
+  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){
+  value *new_value;
+  char *new_string;
+
+  if((env->head)==NULL) {
+    printerr("Too Few Arguments");
+    env->err=1;
+    return;
+  }
+
+  if(env->head->item->type!=string) {
+    printerr("Bad Argument Type");
+    env->err=2;
+    return;
+  }
+
+  new_string= mangle_str((const char *)(env->head->item->content.ptr));
+
+  toss(env);
+  if(env->err) return;
+
+  new_value= malloc(sizeof(value));
+  new_value->content.ptr= new_string;
+  new_value->type= string;
+  new_value->refcount=1;
+
+  push_val(env, new_value);
 }
 
 /* Push a symbol onto the stack. */
@@ -161,6 +263,8 @@
   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));
@@ -193,7 +297,14 @@
       handle= dlopen(NULL, RTLD_LAZY);
 
     funcptr= dlsym(handle, in_string); /* Get function pointer */
-    if(dlerror()==NULL) { 	/* If a function was found */
+    dlerr=dlerror();
+    if(dlerr != NULL) {		/* If no function was found */
+      mangled=mangle_str(in_string);
+      funcptr= dlsym(handle, mangled); /* try mangling it */
+      free(mangled);
+      dlerr=dlerror();
+    }
+    if(dlerr==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 */
@@ -202,53 +313,7 @@
       new_fvalue->refcount= 1;
     }
   }
-  push(&(env->head), new_item);
-}
-
-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);
-      break;
-    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;
-    }
-  }
-}
-
-/* Discard the top element of the stack. */
-extern void toss(environment *env)
-{
-  stackitem *temp= env->head;
-
-  if((env->head)==NULL) {
-    printerr("Too Few Arguments");
-    env->err=1;
-    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(env, new_item);
 }
 
 /* Print newline. */
@@ -284,9 +349,6 @@
   case list:
     push_sym(env, "list");
     break;
-  default:
-    push_sym(env, "unknown");
-    break;
   }
 }    
 
@@ -298,10 +360,10 @@
     printf("%d", stack_head->item->content.val);
     break;
   case string:
-    printf("\"%s\"", (char*)stack_head->item->content.ptr);
+    printf("%s", (char*)stack_head->item->content.ptr);
     break;
   case symb:
-    printf("'%s'", ((symbol *)(stack_head->item->content.ptr))->id);
+    printf("%s", ((symbol *)(stack_head->item->content.ptr))->id);
     break;
   case func:
     printf("#<function %p>", (funcp)(stack_head->item->content.ptr));
@@ -317,9 +379,6 @@
     }
     printf("]");
     break;
-  default:
-    printf("#<unknown %p>", (stack_head->item->content.ptr));
-    break;
   }
 }
 
@@ -350,8 +409,6 @@
   nl();
 }
 
-
-
 /* Prints the stack. */
 extern void printstack(environment *env)
 {
@@ -367,13 +424,7 @@
 {
   stackitem *temp= env->head;
   
-  if((env->head)==NULL) {
-    printerr("Too Few Arguments");
-    env->err=1;
-    return;
-  }
-
-  if(env->head->next==NULL) {
+  if(env->head==NULL || env->head->next==NULL) {
     printerr("Too Few Arguments");
     env->err=1;
     return;
@@ -384,14 +435,21 @@
   env->head->next= 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;
+  stackitem *temp= env->head;
+  
+  if(env->head==NULL || env->head->next==NULL
+      || env->head->next->next==NULL) {
+    printerr("Too Few Arguments");
+    env->err=1;
+    return;
+  }
 
-  return out_item;
+  env->head= env->head->next->next;
+  temp->next->next= env->head->next;
+  env->head->next= temp;
 }
 
 /* Recall a value from a symbol, if bound */
@@ -419,7 +477,7 @@
   }
   toss(env);		/* toss the symbol */
   if(env->err) return;
-  push_val(&(env->head), val); /* Return its bound value */
+  push_val(env, val); /* Return its bound value */
 }
 
 /* If the top element is a symbol, determine if it's bound to a
@@ -428,51 +486,109 @@
 extern void eval(environment *env)
 {
   funcp in_func;
+  value* temp_val;
+  stackitem* iterator;
+
   if(env->head==NULL) {
     printerr("Too Few Arguments");
     env->err=1;
     return;
   }
 
-  /* if it's a symbol */
-  if(env->head->item->type==symb) {
+ eval_start:
 
+  switch(env->head->item->type) {
+    /* if it's a symbol */
+  case symb:
     rcl(env);			/* get its contents */
     if(env->err) return;
     if(env->head->item->type!=symb){ /* don't recurse symbols */
-      eval(env);			/* evaluate the value */
-      return;
+      goto eval_start;
     }
-  }
+    return;
 
-  /* If it's a lone function value, run it */
-  if(env->head->item->type==func) {
+    /* If it's a lone function value, run it */
+  case func:
     in_func= (funcp)(env->head->item->content.ptr);
     toss(env); 
     if(env->err) return;
-    (*in_func)(env);
+    return (*in_func)(env);
+
+    /* If it's a list */
+  case list:
+    temp_val= env->head->item;
+    env->head->item->refcount++;
+    toss(env);
+    if(env->err) return;
+    iterator= (stackitem*)temp_val->content.ptr;
+    while(iterator!=NULL) {
+      push_val(env, iterator->item);
+      if(env->head->item->type==symb
+	&& strcmp(";", ((symbol*)(env->head->item->content.ptr))->id)==0) {
+	toss(env);
+	if(env->err) return;
+	if(iterator->next == NULL){
+	  free_val(temp_val);
+	  goto eval_start;
+	}
+	eval(env);
+	if(env->err) return;
+      }
+      iterator= iterator->next;
+    }
+    free_val(temp_val);
+    return;
+
+  default:
+    return;
   }
 }
 
+/* Reverse (flip) a list */
+extern void rev(environment *env){
+  stackitem *old_head, *new_head, *item;
+
+  if((env->head)==NULL) {
+    printerr("Too Few Arguments");
+    env->err=1;
+    return;
+  }
+
+  if(env->head->item->type!=list) {
+    printerr("Bad Argument Type");
+    env->err=2;
+    return;
+  }
+
+  old_head=(stackitem *)(env->head->item->content.ptr);
+  new_head=NULL;
+  while(old_head != NULL){
+    item=old_head;
+    old_head=old_head->next;
+    item->next=new_head;
+    new_head=item;
+  }
+  env->head->item->content.ptr=new_head;
+}
+
 /* Make a list. */
 extern void pack(environment *env)
 {
-  void* delimiter;
   stackitem *iterator, *temp;
   value *pack;
 
-  delimiter= env->head->item->content.ptr; /* Get delimiter */
-  toss(env);
-
   iterator= env->head;
 
-  if(iterator==NULL || iterator->item->content.ptr==delimiter) {
+  if(iterator==NULL
+     || (iterator->item->type==symb
+     && ((symbol*)(iterator->item->content.ptr))->id[0]=='[')) {
     temp= NULL;
     toss(env);
   } else {
     /* Search for first delimiter */
     while(iterator->next!=NULL
-	  && iterator->next->item->content.ptr!=delimiter)
+	  && (iterator->next->item->type!=symb
+	  || ((symbol*)(iterator->next->item->content.ptr))->id[0]!='['))
       iterator= iterator->next;
     
     /* Extract list */
@@ -490,84 +606,8 @@
   pack->content.ptr= temp;
   pack->refcount= 1;
 
-  temp= malloc(sizeof(stackitem));
-  temp->item= pack;
-
-  push(&(env->head), temp);
-}
-
-/* Parse input. */
-void 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;
-  }
-   
-  stack_read(env, rest);
-  
-  free(rest);
+  push_val(env, pack);
+  rev(env);
 }
 
 /* Relocate elements of the list on the stack. */
@@ -587,6 +627,11 @@
     return;
   }
 
+  rev(env);
+
+  if(env->err)
+    return;
+
   /* The first list element is the new stack head */
   new_head= temp= env->head->item->content.ptr;
 
@@ -603,33 +648,6 @@
 
 }
 
-/* Reverse a list */
-extern void rev(environment *env){
-  stackitem *old_head, *new_head, *item;
-
-  if((env->head)==NULL) {
-    printerr("Too Few Arguments");
-    env->err=1;
-    return;
-  }
-
-  if(env->head->item->type!=list) {
-    printerr("Bad Argument Type");
-    env->err=2;
-    return;
-  }
-
-  old_head=(stackitem *)(env->head->item->content.ptr);
-  new_head=NULL;
-  while(old_head != NULL){
-    item=old_head;
-    old_head=old_head->next;
-    item->next=new_head;
-    new_head=item;
-  }
-  env->head->item->content.ptr=new_head;
-}
-
 /* Compares two elements by reference. */
 extern void eq(environment *env)
 {
@@ -648,7 +666,7 @@
   result= (left==right);
   
   toss(env); toss(env);
-  push_int(&(env->head), result);
+  push_int(env, result);
 }
 
 /* Negates the top element on the stack. */
@@ -670,7 +688,7 @@
 
   val= env->head->item->content.val;
   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
@@ -776,26 +794,454 @@
 
 /* Returns the current error number to the stack */
 extern void errn(environment *env){
-  push_int(&(env->head), env->err);
+  push_int(env, env->err);
 }
 
+extern void read(environment*);
+
 int main()
 {
   environment myenv;
-  char in_string[100];
 
   init_env(&myenv);
 
-  printf("okidok\n ");
-
-  while(fgets(in_string, 100, stdin) != NULL) {
-    stack_read(&myenv, in_string);
+  while(1) {
+    if(myenv.in_string==NULL)
+      printstack(&myenv);
+    read(&myenv);
     if(myenv.err) {
       printf("(error %d) ", myenv.err);
       myenv.err=0;
+    } else if(myenv.head!=NULL
+	      && myenv.head->item->type==symb
+	      && ((symbol*)(myenv.head->item->content.ptr))->id[0]==';') {
+      toss(&myenv); 		/* No error check in main */
+      eval(&myenv);
     }
-    printf("okidok\n ");
   }
+  quit(&myenv);
+  return EXIT_FAILURE;
+}
 
-  exit(EXIT_SUCCESS);
+/* + */
+extern void sx_2b(environment *env) {
+  int a, b;
+  size_t len;
+  char* new_string;
+  value *a_val, *b_val;
+
+  if((env->head)==NULL || env->head->next==NULL) {
+    printerr("Too Few Arguments");
+    env->err=1;
+    return;
+  }
+
+  if(env->head->item->type==string
+     && env->head->next->item->type==string) {
+    a_val= env->head->item;
+    b_val= env->head->next->item;
+    a_val->refcount++;
+    b_val->refcount++;
+    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);
+    free_val(a_val); free_val(b_val);
+    push_cstring(env, new_string);
+    free(new_string);
+    return;
+  }
+  
+  if(env->head->item->type!=integer
+     || env->head->next->item->type!=integer) {
+    printerr("Bad Argument Type");
+    env->err=2;
+    return;
+  }
+  a=env->head->item->content.val;
+  toss(env);
+  if(env->err) return;
+  if(env->head->item->refcount == 1)
+    env->head->item->content.val += a;
+  else {
+    b=env->head->item->content.val;
+    toss(env);
+    if(env->err) return;
+    push_int(env, a+b);
+  }
+}
+
+/* - */
+extern void sx_2d(environment *env) {
+  int a, b;
+
+  if((env->head)==NULL || env->head->next==NULL) {
+    printerr("Too Few Arguments");
+    env->err=1;
+    return;
+  }
+  
+  if(env->head->item->type!=integer
+     || env->head->next->item->type!=integer) {
+    printerr("Bad Argument Type");
+    env->err=2;
+    return;
+  }
+  a=env->head->item->content.val;
+  toss(env);
+  if(env->err) return;
+  if(env->head->item->refcount == 1)
+    env->head->item->content.val -= a;
+  else {
+    b=env->head->item->content.val;
+    toss(env);
+    if(env->err) return;
+    push_int(env, b-a);
+  }
+}
+
+/* > */
+extern void sx_3e(environment *env) {
+  int a, b;
+
+  if((env->head)==NULL || env->head->next==NULL) {
+    printerr("Too Few Arguments");
+    env->err=1;
+    return;
+  }
+  
+  if(env->head->item->type!=integer
+     || env->head->next->item->type!=integer) {
+    printerr("Bad Argument Type");
+    env->err=2;
+    return;
+  }
+  a=env->head->item->content.val;
+  toss(env);
+  if(env->err) return;
+  if(env->head->item->refcount == 1)
+    env->head->item->content.val = (env->head->item->content.val > a);
+  else {
+    b=env->head->item->content.val;
+    toss(env);
+    if(env->err) return;
+    push_int(env, b>a);
+  }
+}
+
+/* Return copy of a value */
+value *copy_val(value *old_value){
+  stackitem *old_item, *new_item, *prev_item;
+
+  value *new_value=malloc(sizeof(value));
+
+  new_value->type=old_value->type;
+  new_value->refcount=0;	/* This is increased if/when this
+				   value is referenced somewhere, like
+				   in a stack item or a variable */
+  switch(old_value->type){
+  case integer:
+    new_value->content.val=old_value->content.val;
+    break;
+  case string:
+    (char *)(new_value->content.ptr)
+      = strdup((char *)(old_value->content.ptr));
+    break;
+  case func:
+  case symb:
+    new_value->content.ptr=old_value->content.ptr;
+    break;
+  case list:
+    new_value->content.ptr=NULL;
+
+    prev_item=NULL;
+    old_item=(stackitem *)(old_value->content.ptr);
+
+    while(old_item != NULL) {	/* While list is not empty */
+      new_item= malloc(sizeof(stackitem));
+      new_item->item=copy_val(old_item->item); /* recurse */
+      new_item->next=NULL;
+      if(prev_item != NULL)	/* If this wasn't the first item */
+	prev_item->next=new_item; /* point the previous item to the
+                                     new item */
+      else
+	new_value->content.ptr=new_item;
+      old_item=old_item->next;
+      prev_item=new_item;
+    }	  
+    break;
+  }
+  return new_value;
+}
+
+/* duplicates an item on the stack */
+extern void dup(environment *env) {
+  if((env->head)==NULL) {
+    printerr("Too Few Arguments");
+    env->err=1;
+    return;
+  }
+  push_val(env, copy_val(env->head->item));
+}
+
+/* "if", If-Then */
+extern void sx_6966(environment *env) {
+
+  int truth;
+
+  if((env->head)==NULL || env->head->next==NULL) {
+    printerr("Too Few Arguments");
+    env->err=1;
+    return;
+  }
+
+  if(env->head->next->item->type != integer) {
+    printerr("Bad Argument Type");
+    env->err=2;
+    return;
+  }
+  
+  swap(env);
+  if(env->err) return;
+  
+  truth=env->head->item->content.val;
+
+  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)==NULL || env->head->next==NULL
+     || env->head->next->next==NULL) {
+    printerr("Too Few Arguments");
+    env->err=1;
+    return;
+  }
+
+  if(env->head->next->next->item->type != integer) {
+    printerr("Bad Argument Type");
+    env->err=2;
+    return;
+  }
+  
+  rot(env);
+  if(env->err) return;
+  
+  truth=env->head->item->content.val;
+
+  toss(env);
+  if(env->err) return;
+
+  if(!truth)
+    swap(env);
+  if(env->err) return;
+
+  toss(env);
+  if(env->err) return;
+
+  eval(env);
+}
+
+/* while */
+extern void sx_7768696c65(environment *env) {
+
+  int truth;
+  value *loop, *test;
+
+  if((env->head)==NULL || env->head->next==NULL) {
+    printerr("Too Few Arguments");
+    env->err=1;
+    return;
+  }
+
+  loop= env->head->item;
+  loop->refcount++;
+  toss(env); if(env->err) return;
+
+  test= env->head->item;
+  test->refcount++;
+  toss(env); if(env->err) return;
+
+  do {
+    push_val(env, test);
+    eval(env);
+    
+    if(env->head->item->type != integer) {
+      printerr("Bad Argument Type");
+      env->err=2;
+      return;
+    }
+    
+    truth= env->head->item->content.val;
+    toss(env); if(env->err) return;
+    
+    if(truth) {
+      push_val(env, loop);
+      eval(env);
+    } else {
+      toss(env);
+    }
+  
+  } while(truth);
+
+  free_val(test);
+  free_val(loop);
+}
+
+/* For-loop */
+extern void sx_666f72(environment *env) {
+  
+  value *loop, *foo;
+  stackitem *iterator;
+  
+  if((env->head)==NULL || env->head->next==NULL) {
+    printerr("Too Few Arguments");
+    env->err=1;
+    return;
+  }
+
+  if(env->head->next->item->type != list) {
+    printerr("Bad Argument Type");
+    env->err=2;
+    return;
+  }
+
+  loop= env->head->item;
+  loop->refcount++;
+  toss(env); if(env->err) return;
+
+  foo= env->head->item;
+  foo->refcount++;
+  toss(env); if(env->err) return;
+
+  iterator= foo->content.ptr;
+
+  while(iterator!=NULL) {
+    push_val(env, iterator->item);
+    push_val(env, loop);
+    eval(env); if(env->err) return;
+    iterator= iterator->next;
+  }
+
+  free_val(loop);
+  free_val(foo);
+}
+
+/* 'to' */
+extern void to(environment *env) {
+  int i, start, ending;
+  stackitem *temp_head;
+  value *temp_val;
+  
+  if((env->head)==NULL || env->head->next==NULL) {
+    printerr("Too Few Arguments");
+    env->err=1;
+    return;
+  }
+
+  if(env->head->item->type!=integer 
+     || env->head->next->item->type!=integer) {
+    printerr("Bad Argument Type");
+    env->err=2;
+    return;
+  }
+
+  ending= env->head->item->content.val;
+  toss(env); if(env->err) return;
+  start= env->head->item->content.val;
+  toss(env); if(env->err) return;
+
+  temp_head= env->head;
+  env->head= NULL;
+
+  if(ending>=start) {
+    for(i= ending; i>=start; i--)
+      push_int(env, i);
+  } else {
+    for(i= ending; i<=start; i++)
+      push_int(env, i);
+  }
+
+  temp_val= malloc(sizeof(value));
+  temp_val->content.ptr= env->head;
+  temp_val->refcount= 1;
+  temp_val->type= list;
+  env->head= temp_head;
+  push_val(env, temp_val);
+}
+
+/* Read a string */
+extern void readline(environment *env) {
+  char in_string[101];
+
+  fgets(in_string, 100, stdin);
+  push_cstring(env, in_string);
+}
+
+/* Read a value and place on stack */
+extern void read(environment *env) {
+  const char symbform[]= "%[a-zA-Z0-9!$%*+./:<=>?@^_~-]%[\001-\377]";
+  const char strform[]= "\"%[^\"]\"%[\001-\377]";
+  const char intform[]= "%i%[\001-\377]";
+  const char blankform[]= "%*[ \t]%[\001-\377]";
+  const char ebrackform[]= "%*1[]]%[\001-\377]";
+  const char semicform[]= "%*1[;]%[\001-\377]";
+  const char bbrackform[]= "%*1[[]%[\001-\377]";
+
+  int itemp;
+  static int depth= 0;
+  char *rest, *match;
+  size_t inlength;
+
+  if(env->in_string==NULL) {
+    readline(env); if(env->err) return;
+    
+    env->in_string= malloc(strlen(env->head->item->content.ptr)+1);
+    strcpy(env->in_string, env->head->item->content.ptr);
+    toss(env); if(env->err) return;
+  }
+  
+  inlength= strlen(env->in_string)+1;
+  match= malloc(inlength);
+  rest= malloc(inlength);
+
+  if(sscanf(env->in_string, blankform, rest)) {
+    ; 
+  } else if(sscanf(env->in_string, intform, &itemp, rest) > 0) {
+    push_int(env, itemp);
+  } else if(sscanf(env->in_string, strform, match, rest) > 0) {
+    push_cstring(env, match);
+  } else if(sscanf(env->in_string, symbform, match, rest) > 0) {
+    push_sym(env, match);
+  } else if(sscanf(env->in_string, ebrackform, rest) > 0) {
+    pack(env); if(env->err) return;
+    if(depth!=0) depth--;
+  } else if(sscanf(env->in_string, semicform, rest) > 0) {
+    push_sym(env, ";");
+  } else if(sscanf(env->in_string, bbrackform, rest) > 0) {
+    push_sym(env, "[");
+    depth++;
+  } else {
+    free(rest);
+    rest= NULL;
+  }
+      
+  free(env->in_string);
+  free(match);
+
+  env->in_string= rest;
+
+  if(depth)
+    return read(env);
 }