diff --git a/eval.c b/eval.c
index 30ad2bb..1519f2c 100644
--- a/eval.c
+++ b/eval.c
@@ -1,7 +1,7 @@
 /*
  *  module  : eval.c
- *  version : 1.20
- *  date    : 04/11/24
+ *  version : 1.22
+ *  date    : 04/26/24
  */
 #include "globals.h"
 
@@ -25,7 +25,7 @@ static void set_alarm(int num)
 }
 #endif
 
-static void trace(pEnv env, FILE *fp)
+void trace(pEnv env, FILE *fp)
 {
     writestack(env, env->stck, fp);
     if (env->debugging == 2) {
@@ -54,7 +54,7 @@ void evaluate(pEnv env, NodeList *list)
 #if ALARM
 	if (time_out) {
 	    time_out = 0;
-	    execerror(env->filename, "more time", "evaluate");
+	    execerror("more time", "evaluate");
 	}
 #endif
 	if (env->debugging)
@@ -66,7 +66,7 @@ void evaluate(pEnv env, NodeList *list)
 	    if (ent.u.body)
 		prog(env, ent.u.body);
 	    else if (env->undeferror)
-		execerror(env->filename, "definition", ent.name);
+		execerror("definition", ent.name);
 	    continue;
 	case ANON_FUNCT_:
 	    (*node.u.proc)(env);
diff --git a/globals.h b/globals.h
index 448da0d..8b9c485 100644
--- a/globals.h
+++ b/globals.h
@@ -1,7 +1,7 @@
 /*
     module  : globals.h
-    version : 1.42
-    date    : 04/11/24
+    version : 1.46
+    date    : 05/02/24
 */
 #ifndef GLOBALS_H
 #define GLOBALS_H
@@ -127,6 +127,7 @@ typedef enum {
 typedef enum {
     ABORT_NONE,
     ABORT_RETRY,
+    ABORT_ERROR,
     ABORT_QUIT
 } Abort;
 
@@ -188,6 +189,7 @@ KHASH_MAP_INIT_INT64(Funtab, int)
  * Global variables are stored locally in the main function.
  */
 typedef struct Env {
+    jmp_buf finclude;		/* return point in finclude */
     double calls;		/* statistics */
     double opers;
     vector(Token) *tokens;	/* read ahead table */
@@ -231,6 +233,7 @@ typedef struct Env {
     unsigned char overwrite;
     unsigned char printing;
     unsigned char recurse;
+    unsigned char finclude_busy;
 } Env;
 
 typedef struct table_t {
@@ -246,6 +249,7 @@ void initcompile(pEnv env);
 void exitcompile(pEnv env);
 void compileprog(pEnv env, NodeList *list);
 /* eval.c */
+void trace(pEnv env, FILE *fp);
 void evaluate(pEnv env, NodeList *list);
 /* exec.c */
 void execute(pEnv env, NodeList *list);
@@ -258,8 +262,6 @@ int my_yylex(pEnv env);
 int get_input(void);
 /* main.c */
 void abortexecution_(int num);
-void stats(pEnv env);
-void dump(pEnv env);
 /* modl.c */
 void savemod(int *hide, int *modl, int *hcnt);
 void undomod(int hide, int modl, int hcnt);
@@ -299,7 +301,7 @@ void save(pEnv env, NodeList *list, int num, int remove);
 /* scan.c */
 void inilinebuffer(pEnv env);
 void include(pEnv env, char *str);
-int yywrap(void);
+int my_yywrap(pEnv env);	/* yywrap replacement */
 void my_error(char *str, YYLTYPE *bloc);
 void yyerror(pEnv env, char *str);
 /* util.c */
@@ -310,7 +312,7 @@ void writefactor(pEnv env, Node node, FILE *fp);
 void writeterm(pEnv env, NodeList *list, FILE *fp);
 void writestack(pEnv env, NodeList *list, FILE *fp);
 /* xerr.c */
-void execerror(char *filename, char *message, char *op);
+void execerror(char *message, char *op);
 /* ylex.c */
 int yylex(pEnv env);
 /* byte.c */
diff --git a/lexr.l b/lexr.l
index d302096..0242ca5 100644
--- a/lexr.l
+++ b/lexr.l
@@ -1,13 +1,17 @@
 %{
 /*
     module  : lexr.l
-    version : 1.31
-    date    : 03/22/24
+    version : 1.33
+    date    : 05/06/24
 */
 #include "globals.h"
 
 #define YY_DECL		int my_yylex(pEnv env)
+#define YY_NO_INPUT
 #define YY_NO_UNPUT
+#define YY_SKIP_YYWRAP
+
+#define yywrap()	my_yywrap(env)
 
 #define OUT_OF_COM	0
 #define WITHIN_COM	1
@@ -15,8 +19,8 @@
 #define MAX_FILLER	3	/* allow max. three empty lines */
 
 char line[INPLINEMAX + 1];
-static int linenum, linepos;
 
+static int linenum, linepos;
 static int include_stack_ptr;
 static YY_BUFFER_STATE include_stack[INPSTACKMAX];
 
@@ -155,11 +159,3 @@ INLINE[ \t]*	return CONST_;
 .		return yytext[0];
 
 %%
-
-/*
- * Supporting getch, reading from the stack of input files, like get.
- */
-int get_input(void)
-{
-    return input();
-}
diff --git a/main.c b/main.c
index 7ee960d..b11b796 100644
--- a/main.c
+++ b/main.c
@@ -1,15 +1,18 @@
 /*
  *  module  : main.c
- *  version : 1.38
- *  date    : 04/11/24
+ *  version : 1.44
+ *  date    : 05/06/24
  */
 #include "globals.h"
 
 extern FILE *yyin;			/* lexr.c */
 
+static jmp_buf begin;			/* restart with empty program */
+
 char *bottom_of_stack;			/* used in gc.c */
 
-static jmp_buf begin;			/* restart with empty program */
+static void stats(pEnv env);
+static void dump(pEnv env);
 
 /*
  * abort execution and restart reading from yyin. In the NOBDW version the
@@ -17,6 +20,7 @@ static jmp_buf begin;			/* restart with empty program */
  */
 void abortexecution_(int num)
 {
+    fflush(stdin);
     longjmp(begin, num);
 }
 
@@ -24,7 +28,7 @@ void abortexecution_(int num)
  * options - print help on startup options and exit: options are those that
  *	     cannot be set from within the language itself.
  */
-void options(pEnv env)
+static void options(pEnv env)
 {
     printf("JOY  -  compiled at %s on %s", __TIME__, __DATE__);
 #ifdef VERS
@@ -71,7 +75,7 @@ void options(pEnv env)
 #if 0
     printf("  -q : operate in quiet mode\n");
 #endif
-    printf("  -r : recurse w/o using the call stack\n");
+    printf("  -r : print without using recursion\n");
     printf("  -s : dump symbol table after execution\n");
     printf("  -t : print a trace of program execution\n");
     printf("  -u : set the undeferror flag (0,1)\n");
@@ -88,7 +92,7 @@ void options(pEnv env)
 #endif
 }
 
-void unknown_opt(pEnv env, char *exe, int ch)
+static void unknown_opt(pEnv env, char *exe, int ch)
 {
     printf("Unknown option argument: \"-%c\"\n", ch);
     printf("More info with: \"%s -h\"\n", exe);
@@ -211,7 +215,7 @@ int my_main(int argc, char **argv)
 #if 0
 		case 'v' : verbose = 0; break;
 #endif
-		case 'w' : env.overwrite = 0; break;
+		case 'w' : remove("joy.log"); env.overwrite = 0; break;
 		case 'x' : pstats = 1; break;
 #if YYDEBUG
 		case 'y' : yydebug = 1; break;
@@ -321,8 +325,8 @@ int my_main(int argc, char **argv)
      * initialize standard input and output.
      */
 #ifdef KEYBOARD
-    if (raw && strcmp(env.filename, "stdin")) {	/* filename required */
-	env.autoput = 0;		/* disable autoput */
+    if (raw && strcmp(env.filename, "stdin")) {	/* raw requires filename */
+	env.autoput = 0;		/* disable autoput and usrlib.joy */
 	env.autoput_set = 1;		/* prevent enabling autoput */
 	SetRaw(&env);
     } else				/* keep output buffered */
@@ -334,8 +338,10 @@ int my_main(int argc, char **argv)
     if (mustinclude)
 	include(&env, "usrlib.joy");	/* start reading from library first */
     rv = setjmp(begin);			/* return here after error or abort */
-    if (rv == ABORT_QUIT || (rv && !joy))
-	goto einde;
+    if (rv == ABORT_ERROR && joy)	/* in case of a runtime error ...   */
+	trace(&env, stderr);		/* ... dump stack and (all of) code */
+    if (rv == ABORT_QUIT || (rv && !joy))	/* in case end of file ...  */
+	goto einde;				/* ... wrap up and exit     */
     /*
      * (re)initialize code.
      */
@@ -376,7 +382,7 @@ int main(int argc, char **argv)
 /*
  * print statistics.
  */
-void stats(pEnv env)
+static void stats(pEnv env)
 {
     printf("%.0f milliseconds CPU\n", (clock() - env->startclock) * 1000.0 /
 	   CLOCKS_PER_SEC);
@@ -390,7 +396,7 @@ void stats(pEnv env)
 /*
  * dump the symbol table, from last to first.
  */
-void dump(pEnv env)
+static void dump(pEnv env)
 {
     int i;
     Entry ent;
diff --git a/modl.c b/modl.c
index ac03c7a..f943640 100644
--- a/modl.c
+++ b/modl.c
@@ -1,7 +1,7 @@
 /*
     module  : modl.c
-    version : 1.7
-    date    : 03/21/24
+    version : 1.8
+    date    : 04/23/24
 */
 #include "globals.h"
 
@@ -20,7 +20,7 @@ static int module_index = -1;
 
 /*
  * savemod saves the global variables, to be restored later with undomod.
-*/
+ */
 void savemod(int *hide, int *modl, int *hcnt)
 {
     *hide = hide_index;
@@ -43,7 +43,7 @@ void initmod(pEnv env, char *name)
 {
     if (++module_index >= DISPLAYMAX) {
 	module_index = -1;
-	execerror(env->filename, "index", "display");
+	execerror("index", "display");
     }
     env->module_stack[module_index].name = name;
     env->module_stack[module_index].hide = hide_index;
@@ -62,7 +62,7 @@ void initpriv(pEnv env)
 {
     if (++hide_index >= DISPLAYMAX) {
 	hide_index = -1;
-	execerror(env->filename, "index", "display");
+	execerror("index", "display");
     }
     env->hide_stack[hide_index] = ++hide_count;
     inside_hide = 1;
@@ -117,6 +117,9 @@ char *classify(pEnv env, char *name)
     size_t leng;
     char temp[MAXNUM], *buf = 0, *str;
 
+    /*
+     * if name already has a prefix, there is no need to add another one.
+     */
     if (strchr(name, '.'))
 	return name;
     /*
diff --git a/parm.c b/parm.c
index f39c081..11b29fa 100644
--- a/parm.c
+++ b/parm.c
@@ -1,7 +1,7 @@
 /*
     module  : parm.c
-    date    : 1.16
-    version : 04/11/24
+    date    : 1.20
+    version : 05/06/24
 */
 #include "globals.h"
 
@@ -26,7 +26,7 @@ void checknum(char *name, int num, int leng, char *file)
 		break;
 	}
     if (ptr)
-	execerror(name, ptr, file);
+	execerror(ptr, file);
 }
 
 /*
@@ -53,253 +53,254 @@ void parm(pEnv env, int num, Params type, char *file)
 	checknum(env->filename, num, leng, file);
 	first = pvec_lst(env->stck);
 	if (first.op != LIST_)
-	    execerror(env->filename, "quotation as top parameter", file);
+	    execerror("quotation as top parameter", file);
 	break;
 /*
     two quotes are needed:
 */
     case WHILE:
 	if (leng < 2)
-	    execerror(env->filename, "two parameters", file);
+	    execerror("two parameters", file);
 	first = pvec_lst(env->stck);
 	second = pvec_nth(env->stck, leng - 2);
 	if (first.op != LIST_)
-	    execerror(env->filename, "quotation as top parameter", file);
+	    execerror("quotation as top parameter", file);
 	if (second.op != LIST_)
-	    execerror(env->filename, "quotation as second parameter", file);
+	    execerror("quotation as second parameter", file);
 	break;
 /*
     three quotes are needed:
 */
     case IFTE:
 	if (leng < 3)
-	    execerror(env->filename, "three parameters", file);
+	    execerror("three parameters", file);
 	first = pvec_lst(env->stck);
 	second = pvec_nth(env->stck, leng - 2);
 	third = pvec_nth(env->stck, leng - 3);
 	if (first.op != LIST_)
-	    execerror(env->filename, "quotation as top parameter", file);
+	    execerror("quotation as top parameter", file);
 	if (second.op != LIST_)
-	    execerror(env->filename, "quotation as second parameter", file);
+	    execerror("quotation as second parameter", file);
 	if (third.op != LIST_)
-	    execerror(env->filename, "quotation as third parameter", file);
+	    execerror("quotation as third parameter", file);
 	break;
 /*
     four quotes are needed:
 */
     case LINREC:
 	if (leng < 4)
-	    execerror(env->filename, "four parameters", file);
+	    execerror("four parameters", file);
 	first = pvec_lst(env->stck);
 	second = pvec_nth(env->stck, leng - 2);
 	third = pvec_nth(env->stck, leng - 3);
 	fourth = pvec_nth(env->stck, leng - 4);
 	if (first.op != LIST_)
-	    execerror(env->filename, "quotation as top parameter", file);
+	    execerror("quotation as top parameter", file);
 	if (second.op != LIST_)
-	    execerror(env->filename, "quotation as second parameter", file);
+	    execerror("quotation as second parameter", file);
 	if (third.op != LIST_)
-	    execerror(env->filename, "quotation as third parameter", file);
+	    execerror("quotation as third parameter", file);
 	if (fourth.op != LIST_)
-	    execerror(env->filename, "quotation as fourth parameter", file);
+	    execerror("quotation as fourth parameter", file);
 	break;
 /*
     list is needed:
 */
     case HELP:
 	if (leng < 1)
-	    execerror(env->filename, "one parameter", file);
+	    execerror("one parameter", file);
 	first = pvec_lst(env->stck);
 	if (first.op != LIST_)
-	    execerror(env->filename, "list", file);
+	    execerror("list", file);
 	break;
 /*
     list is needed as second parameter:
 */
     case INFRA:
 	if (leng < 2)
-	    execerror(env->filename, "two parameters", file);
+	    execerror("two parameters", file);
 	first = pvec_lst(env->stck);
 	second = pvec_nth(env->stck, leng - 2);
 	if (first.op != LIST_)
-	    execerror(env->filename, "quotation as top parameter", file);
+	    execerror("quotation as top parameter", file);
 	if (second.op != LIST_)
-	    execerror(env->filename, "list as second parameter", file);
+	    execerror("list as second parameter", file);
 	break;
 /*
     float or integer is needed:
 */
     case UFLOAT:
 	if (leng < 1)
-	    execerror(env->filename, "one parameter", file);
+	    execerror("one parameter", file);
 	first = pvec_lst(env->stck);
 	if (first.op != FLOAT_ && first.op != INTEGER_)
-	    execerror(env->filename, "float or integer", file);
+	    execerror("float or integer", file);
 	break;
 /*
     two floats or integers are needed:
 */
     case MUL:
 	if (leng < 2)
-	    execerror(env->filename, "two parameters", file);
+	    execerror("two parameters", file);
 	first = pvec_lst(env->stck);
 	second = pvec_nth(env->stck, leng - 2);
 	if (first.op != BIGNUM_ && first.op != FLOAT_ && first.op != INTEGER_)
-	    execerror(env->filename, "float or (big)integer", file);
+	    execerror("float or (big)integer", file);
 	if (second.op != BIGNUM_ && second.op != FLOAT_ &&
 	    second.op != INTEGER_)
-	    execerror(env->filename, "two floats or (big)integers", file);
+	    execerror("two floats or (big)integers", file);
 	break;
 /*
     two floats or integers are needed:
 */
     case BFLOAT:
 	if (leng < 2)
-	    execerror(env->filename, "two parameters", file);
+	    execerror("two parameters", file);
 	first = pvec_lst(env->stck);
 	second = pvec_nth(env->stck, leng - 2);
 	if (first.op != FLOAT_ && first.op != INTEGER_)
-	    execerror(env->filename, "float or integer", file);
+	    execerror("float or integer", file);
 	if (second.op != FLOAT_ && second.op != INTEGER_)
-	    execerror(env->filename, "two floats or integers", file);
+	    execerror("two floats or integers", file);
 	break;
 /*
     file is needed:
 */
     case FGET:
 	if (leng < 1)
-	    execerror(env->filename, "one parameter", file);
+	    execerror("one parameter", file);
 	first = pvec_lst(env->stck);
 	if (first.op != FILE_ || !first.u.fil)
-	    execerror(env->filename, "file", file);
+	    execerror("file", file);
 	break;
 /*
     file is needed as second parameter:
 */
     case FPUT:
 	if (leng < 2)
-	    execerror(env->filename, "two parameters", file);
+	    execerror("two parameters", file);
 	second = pvec_nth(env->stck, leng - 2);
 	if (second.op != FILE_ || !second.u.fil)
-	    execerror(env->filename, "file", file);
+	    execerror("file", file);
 	break;
 /*
     string is needed:
 */
     case STRFTIME:
 	if (leng < 2)
-	    execerror(env->filename, "two parameters", file);
+	    execerror("two parameters", file);
 	first = pvec_lst(env->stck);
 	second = pvec_nth(env->stck, leng - 2);
 	if (first.op != STRING_)
-	    execerror(env->filename, "string", file);
+	    execerror("string", file);
 	if (second.op != LIST_)
-	    execerror(env->filename, "list as second parameter", file);
+	    execerror("list as second parameter", file);
 	break;
     case FPUTCHARS:
 	if (leng < 2)
-	    execerror(env->filename, "two parameters", file);
+	    execerror("two parameters", file);
 	first = pvec_lst(env->stck);
 	second = pvec_nth(env->stck, leng - 2);
 	if (first.op != STRING_ && first.op != BIGNUM_)
-	    execerror(env->filename, "string", file);
+	    execerror("string", file);
 	if (second.op != FILE_ || !second.u.fil)
-	    execerror(env->filename, "file", file);
+	    execerror("file", file);
 	break;
     case STRTOD:
 	if (leng < 1)
-	    execerror(env->filename, "one parameter", file);
+	    execerror("one parameter", file);
 	first = pvec_lst(env->stck);
 	if (first.op != STRING_ && first.op != BIGNUM_)
-	    execerror(env->filename, "string", file);
+	    execerror("string", file);
 	break;
 /*
     string is needed as second parameter:
 */
     case FOPEN:
 	if (leng < 2)
-	    execerror(env->filename, "two parameters", file);
+	    execerror("two parameters", file);
 	first = pvec_lst(env->stck);
 	second = pvec_nth(env->stck, leng - 2);
 	if (first.op != STRING_)
-	    execerror(env->filename, "string", file);
+	    execerror("string", file);
 	if (second.op != STRING_)
-	    execerror(env->filename, "string as second parameter", file);
+	    execerror("string as second parameter", file);
 	break;
 /*
     integer is needed:
 */
     case UNMKTIME:
 	if (leng < 1)
-	    execerror(env->filename, "one parameter", file);
+	    execerror("one parameter", file);
 	first = pvec_lst(env->stck);
 	if (first.op != INTEGER_)
-	    execerror(env->filename, "integer", file);
+	    execerror("integer", file);
 	break;
     case FREAD:
 	if (leng < 2)
-	    execerror(env->filename, "two parameters", file);
+	    execerror("two parameters", file);
 	first = pvec_lst(env->stck);
 	second = pvec_nth(env->stck, leng - 2);
-	if (first.op != INTEGER_)
-	    execerror(env->filename, "integer", file);
+	if (first.op != INTEGER_ && first.op != CHAR_ && first.op != BOOLEAN_)
+	    execerror("numeric", file);
 	if (second.op != FILE_ || !second.u.fil)
-	    execerror(env->filename, "file", file);
+	    execerror("file", file);
 	break;
     case LDEXP:
 	if (leng < 2)
-	    execerror(env->filename, "two parameters", file);
+	    execerror("two parameters", file);
 	first = pvec_lst(env->stck);
 	second = pvec_nth(env->stck, leng - 2);
 	if (first.op != INTEGER_)
-	    execerror(env->filename, "integer", file);
+	    execerror("integer", file);
 	if (second.op != FLOAT_ && second.op != INTEGER_)
-	    execerror(env->filename, "float or integer as second parameter",
-		      file);
+	    execerror("float or integer as second parameter", file);
 	break;
     case STRTOL:
 	if (leng < 2)
-	    execerror(env->filename, "two parameters", file);
+	    execerror("two parameters", file);
 	first = pvec_lst(env->stck);
 	second = pvec_nth(env->stck, leng - 2);
 	if (first.op != INTEGER_)
-	    execerror(env->filename, "integer", file);
+	    execerror("integer", file);
 	if (second.op != STRING_ && second.op != BIGNUM_)
-	    execerror(env->filename, "string as second parameter", file);
+	    execerror("string as second parameter", file);
 	break;
 /*
     two integers are needed:
 */
     case FSEEK:
 	if (leng < 3)
-	    execerror(env->filename, "three parameters", file);
+	    execerror("three parameters", file);
 	first = pvec_lst(env->stck);
 	second = pvec_nth(env->stck, leng - 2);
 	third = pvec_nth(env->stck, leng - 3);
 	if (first.op != INTEGER_ || second.op != INTEGER_)
-	    execerror(env->filename, "two integers", file);
+	    execerror("two integers", file);
 	if (third.op != FILE_ || !third.u.fil)
-	    execerror(env->filename, "file", file);
+	    execerror("file", file);
 	break;
 /*
     integer is needed as second parameter:
 */
     case TIMES:
 	if (leng < 2)
-	    execerror(env->filename, "two parameters", file);
+	    execerror("two parameters", file);
 	first = pvec_lst(env->stck);
 	second = pvec_nth(env->stck, leng - 2);
 	if (first.op != LIST_)
-	    execerror(env->filename, "quotation as top parameter", file);
+	    execerror("quotation as top parameter", file);
 	if (second.op != INTEGER_)
-	    execerror(env->filename, "integer as second parameter", file);
+	    execerror("integer as second parameter", file);
+	if (second.u.num < 0)
+	    execerror("non-negative integer", file);
 	break;
 /*
     numeric type is needed:
 */
     case MAXMIN:
 	if (leng < 2)
-	    execerror(env->filename, "two parameters", file);
+	    execerror("two parameters", file);
 	first = pvec_lst(env->stck);
 	second = pvec_nth(env->stck, leng - 2);
 	if ((first.op == FLOAT_ || first.op == INTEGER_) &&
@@ -308,27 +309,27 @@ void parm(pEnv env, int num, Params type, char *file)
 	else if (first.op != INTEGER_ && first.op != CHAR_ &&
 		 first.op != BOOLEAN_ && second.op != INTEGER_ &&
 		 second.op != CHAR_ && second.op != BOOLEAN_)
-	    execerror(env->filename, "numeric", file);
+	    execerror("numeric", file);
 	else if (first.op != second.op)
-	    execerror(env->filename, "two parameters of the same type", file);
+	    execerror("two parameters of the same type", file);
 	break;
 /*
     numeric type is needed:
 */
     case PREDSUCC:
 	if (leng < 1)
-	    execerror(env->filename, "one parameter", file);
+	    execerror("one parameter", file);
 	first = pvec_lst(env->stck);
 	if (first.op != INTEGER_ && first.op != CHAR_ && first.op != BOOLEAN_ &&
 	    first.op != BIGNUM_)
-	    execerror(env->filename, "numeric", file);
+	    execerror("numeric", file);
 	break;
 /*
     numeric type is needed as second parameter:
 */
     case PLUSMINUS:
 	if (leng < 2)
-	    execerror(env->filename, "two parameters", file);
+	    execerror("two parameters", file);
 	first = pvec_lst(env->stck);
 	second = pvec_nth(env->stck, leng - 2);
 	if ((first.op == BIGNUM_ || first.op == FLOAT_ || first.op == INTEGER_)
@@ -336,187 +337,187 @@ void parm(pEnv env, int num, Params type, char *file)
 	    second.op == INTEGER_))
 	    ;
 	else if (first.op != INTEGER_)
-	    execerror(env->filename, "integer", file);
+	    execerror("integer", file);
 	else if (second.op != INTEGER_ && second.op != CHAR_)
-	    execerror(env->filename, "numeric as second parameter", file);
+	    execerror("numeric as second parameter", file);
 	break;
 /*
     aggregate parameter is needed:
 */
     case SIZE_:
 	if (leng < 1)
-	    execerror(env->filename, "one parameter", file);
+	    execerror("one parameter", file);
 	first = pvec_lst(env->stck);
 	if (first.op != LIST_ && first.op != STRING_ && first.op != SET_ &&
 	    first.op != BIGNUM_)
-	    execerror(env->filename, "aggregate parameter", file);
+	    execerror("aggregate parameter", file);
 	break;
 /*
     aggregate parameter is needed as second parameter:
 */
     case STEP:
 	if (leng < 2)
-	    execerror(env->filename, "two parameters", file);
+	    execerror("two parameters", file);
 	first = pvec_lst(env->stck);
 	second = pvec_nth(env->stck, leng - 2);
 	if (first.op != LIST_)
-	    execerror(env->filename, "quotation as top parameter", file);
+	    execerror("quotation as top parameter", file);
 	if (second.op != LIST_ && second.op != STRING_ && second.op != SET_ &&
 	    second.op != BIGNUM_)
-	    execerror(env->filename, "aggregate parameter", file);
+	    execerror("aggregate parameter", file);
 	break;
     case TAKE:
 	if (leng < 2)
-	    execerror(env->filename, "two parameters", file);
+	    execerror("two parameters", file);
 	first = pvec_lst(env->stck);
 	second = pvec_nth(env->stck, leng - 2);
 	if (first.op != INTEGER_ || first.u.num < 0)
-	    execerror(env->filename, "non-negative integer", file);
+	    execerror("non-negative integer", file);
 	if (second.op != LIST_ && second.op != STRING_ && second.op != SET_ &&
 	    second.op != BIGNUM_)
-	    execerror(env->filename, "aggregate parameter", file);
+	    execerror("aggregate parameter", file);
 	break;
 /*
     two parameters of the same type are needed:
 */
     case CONCAT:
 	if (leng < 2)
-	    execerror(env->filename, "two parameters", file);
+	    execerror("two parameters", file);
 	first = pvec_lst(env->stck);
 	second = pvec_nth(env->stck, leng - 2);
 	if (first.op != LIST_ && first.op != STRING_ && first.op != SET_ &&
 	    second.op != BIGNUM_)
-	    execerror(env->filename, "aggregate parameter", file);
+	    execerror("aggregate parameter", file);
 	if (first.op != second.op)
-	    execerror(env->filename, "two parameters of the same type", file);
+	    execerror("two parameters of the same type", file);
 	break;
 /*
     specific number of types:
 */
     case ANDORXOR:
 	if (leng < 2)
-	    execerror(env->filename, "two parameters", file);
+	    execerror("two parameters", file);
 	first = pvec_lst(env->stck);
 	second = pvec_nth(env->stck, leng - 2);
 	if (first.op != second.op)
-	    execerror(env->filename, "two parameters of the same type", file);
+	    execerror("two parameters of the same type", file);
 	if (first.op != SET_ && first.op != INTEGER_ && first.op != CHAR_ &&
 	    first.op != BOOLEAN_)
-	    execerror(env->filename, "different type", file);
+	    execerror("different type", file);
 	break;
     case NOT:
 	if (leng < 1)
-	    execerror(env->filename, "one parameter", file);
+	    execerror("one parameter", file);
 	first = pvec_lst(env->stck);
 	if (first.op != SET_ && first.op != INTEGER_ && first.op != CHAR_ &&
 	    first.op != BOOLEAN_)
-	    execerror(env->filename, "different type", file);
+	    execerror("different type", file);
 	break;
 /*
     specific number of types:
 */
     case PRIMREC:
 	if (leng < 3)
-	    execerror(env->filename, "three parameters", file);
+	    execerror("three parameters", file);
 	first = pvec_lst(env->stck);
 	second = pvec_nth(env->stck, leng - 2);
 	third = pvec_nth(env->stck, leng - 3);
 	if (first.op != LIST_ || second.op != LIST_)
-	    execerror(env->filename, "two quotations", file);
+	    execerror("two quotations", file);
 	if (third.op != LIST_ && third.op != STRING_ && third.op != SET_ &&
 	    third.op != INTEGER_)
-	    execerror(env->filename, "different type", file);
+	    execerror("different type", file);
 	break;
 /*
     specific number of types:
 */
     case SMALL:
 	if (leng < 1)
-	    execerror(env->filename, "one parameter", file);
+	    execerror("one parameter", file);
 	first = pvec_lst(env->stck);
 	if (first.op != LIST_ && first.op != STRING_ && first.op != SET_ &&
 	    first.op != INTEGER_ && first.op != BOOLEAN_ && first.op != BIGNUM_)
-	    execerror(env->filename, "different type", file);
+	    execerror("different type", file);
 	break;
 /*
     user defined symbol:
 */
     case BODY:
 	if (leng < 1)
-	    execerror(env->filename, "one parameter", file);
+	    execerror("one parameter", file);
 	first = pvec_lst(env->stck);
 	if (first.op != USR_)
-	    execerror(env->filename, "user defined symbol", file);
+	    execerror("user defined symbol", file);
 	break;
 /*
     valid symbol name:
 */
     case INTERN:
 	if (leng < 1)
-	    execerror(env->filename, "one parameter", file);
+	    execerror("one parameter", file);
 	first = pvec_lst(env->stck);
 	if (first.op != STRING_)
-	    execerror(env->filename, "string", file);
+	    execerror("string", file);
 	/*
 	    a negative number is not a valid name
 	*/
 	if (first.u.str[0] == '-' && isdigit((int)first.u.str[1]))
-	    execerror(env->filename, "valid name", file);
+	    execerror("valid name", file);
 	/*
 	    a name that starts with any of these characters is not valid
 	*/
 	if (strchr("\"#'().0123456789;[]{}", first.u.str[0]))
-	    execerror(env->filename, "valid name", file);
+	    execerror("valid name", file);
 	/*
 	    a name consists of alphanumeric characters, or one of the dashes
 	*/
 	for (i = strlen(first.u.str) - 1; i > 0; i--)
 	     if (!isalnum((int)first.u.str[i]) &&
 		 !strchr("-=_", first.u.str[i]))
-		 execerror(env->filename, "valid name", file);
+		 execerror("valid name", file);
 	break;
 /*
     character:
 */
     case FORMAT:
 	if (leng < 4)
-	    execerror(env->filename, "four parameters", file);
+	    execerror("four parameters", file);
 	first = pvec_lst(env->stck);
 	second = pvec_nth(env->stck, leng - 2);
 	third = pvec_nth(env->stck, leng - 3);
 	fourth = pvec_nth(env->stck, leng - 4);
 	if (first.op != INTEGER_ || second.op != INTEGER_)
-	    execerror(env->filename, "two integers", file);
+	    execerror("two integers", file);
 	if (third.op != CHAR_)
-	    execerror(env->filename, "character", file);
+	    execerror("character", file);
 	if (!strchr("dioxX", third.u.num))
-	    execerror(env->filename, "one of: d i o x X", file);
+	    execerror("one of: d i o x X", file);
 	if (fourth.op != INTEGER_ && fourth.op != CHAR_ &&
 	    fourth.op != BOOLEAN_)
-	    execerror(env->filename, "numeric as fourth parameter", file);
+	    execerror("numeric as fourth parameter", file);
 	break;
     case FORMATF:
 	if (leng < 4)
-	    execerror(env->filename, "four parameters", file);
+	    execerror("four parameters", file);
 	first = pvec_lst(env->stck);
 	second = pvec_nth(env->stck, leng - 2);
 	third = pvec_nth(env->stck, leng - 3);
 	fourth = pvec_nth(env->stck, leng - 4);
 	if (first.op != INTEGER_ || second.op != INTEGER_)
-	    execerror(env->filename, "two integers", file);
+	    execerror("two integers", file);
 	if (third.op != CHAR_)
-	    execerror(env->filename, "character", file);
+	    execerror("character", file);
 	if (!strchr("eEfgG", third.u.num))
-	    execerror(env->filename, "one of: e E f g G", file);
+	    execerror("one of: e E f g G", file);
 	if (fourth.op != FLOAT_)
-	    execerror(env->filename, "float as fourth parameter", file);
+	    execerror("float as fourth parameter", file);
 	break;
 /*
     set member:
 */
     case CONS:
 	if (leng < 2)
-	    execerror(env->filename, "two parameters", file);
+	    execerror("two parameters", file);
 	first = pvec_lst(env->stck);
 	second = pvec_nth(env->stck, leng - 2);
 	switch (first.op) {
@@ -525,15 +526,15 @@ void parm(pEnv env, int num, Params type, char *file)
 	case STRING_:
 	case BIGNUM_:
 	    if (second.op != CHAR_)
-		execerror(env->filename, "character", file);
+		execerror("character", file);
 	    break;
 	case SET_:
 	    if ((second.op != INTEGER_ && second.op != CHAR_) ||
 		 second.u.num < 0 || second.u.num >= SETSIZE)
-		execerror(env->filename, "small numeric", file);
+		execerror("small numeric", file);
 	    break;
 	default:
-	    execerror(env->filename, "aggregate parameter", file);
+	    execerror("aggregate parameter", file);
 	}
 	break;
 /*
@@ -541,7 +542,7 @@ void parm(pEnv env, int num, Params type, char *file)
 */
     case IN_:
 	if (leng < 2)
-	    execerror(env->filename, "two parameters", file);
+	    execerror("two parameters", file);
 	first = pvec_lst(env->stck);
 	second = pvec_nth(env->stck, leng - 2);
 	switch (first.op) {
@@ -551,16 +552,16 @@ void parm(pEnv env, int num, Params type, char *file)
 	case BIGNUM_:
 #if 0
 	    if (second.op != CHAR_)
-		execerror(env->filename, "character", file);
+		execerror("character", file);
 #endif
 	    break;
 	case SET_:
 	    if ((second.op != INTEGER_ && second.op != CHAR_) ||
 		 second.u.num < 0 || second.u.num >= SETSIZE)
-		execerror(env->filename, "small numeric", file);
+		execerror("small numeric", file);
 	    break;
 	default:
-	    execerror(env->filename, "aggregate parameter", file);
+	    execerror("aggregate parameter", file);
 	}
 	break;
 /*
@@ -568,7 +569,7 @@ void parm(pEnv env, int num, Params type, char *file)
 */
     case HAS:
 	if (leng < 2)
-	    execerror(env->filename, "two parameters", file);
+	    execerror("two parameters", file);
 	first = pvec_lst(env->stck);
 	second = pvec_nth(env->stck, leng - 2);
 	switch (second.op) {
@@ -578,16 +579,16 @@ void parm(pEnv env, int num, Params type, char *file)
 	case BIGNUM_:
 #if 0
 	    if (first.op != CHAR_)
-		execerror(env->filename, "character", file);
+		execerror("character", file);
 #endif
 	    break;
 	case SET_:
 	    if ((first.op != INTEGER_ && first.op != CHAR_) ||
 		 first.u.num < 0 || first.u.num >= SETSIZE)
-		execerror(env->filename, "small numeric", file);
+		execerror("small numeric", file);
 	    break;
 	default:
-	    execerror(env->filename, "aggregate parameter", file);
+	    execerror("aggregate parameter", file);
 	}
 	break;
 /*
@@ -595,16 +596,16 @@ void parm(pEnv env, int num, Params type, char *file)
 */
     case CASE:
 	if (leng < 2)
-	    execerror(env->filename, "two parameters", file);
+	    execerror("two parameters", file);
 	first = pvec_lst(env->stck);
 	if (first.op != LIST_)
-	    execerror(env->filename, "list", file);
+	    execerror("list", file);
 	if (!pvec_cnt(first.u.lis))
-	    execerror(env->filename, "non-empty list", file);
+	    execerror("non-empty list", file);
 	for (i = pvec_cnt(first.u.lis) - 1; i >= 0; i--) {
 	    second = pvec_nth(first.u.lis, i);
 	    if (second.op != LIST_)
-		execerror(env->filename, "internal list", file);
+		execerror("internal list", file);
 	}
 	break;
 /*
@@ -612,24 +613,24 @@ void parm(pEnv env, int num, Params type, char *file)
 */
     case FIRST:
 	if (leng < 1)
-	    execerror(env->filename, "one parameter", file);
+	    execerror("one parameter", file);
 	first = pvec_lst(env->stck);
 	switch (first.op) {
 	case LIST_:
 	    if (!pvec_cnt(first.u.lis))
-		execerror(env->filename, "non-empty list", file);
+		execerror("non-empty list", file);
 	    break;
 	case STRING_:
 	case BIGNUM_:
 	    if (!*first.u.str)
-		execerror(env->filename, "non-empty string", file);
+		execerror("non-empty string", file);
 	    break;
 	case SET_:
 	    if (!first.u.set)
-		execerror(env->filename, "non-empty set", file);
+		execerror("non-empty set", file);
 	    break;
 	default:
-	    execerror(env->filename, "aggregate parameter", file);
+	    execerror("aggregate parameter", file);
 	}
 	break;
 /*
@@ -637,66 +638,66 @@ void parm(pEnv env, int num, Params type, char *file)
 */
     case OF:
 	if (leng < 2)
-	    execerror(env->filename, "two parameters", file);
+	    execerror("two parameters", file);
 	first = pvec_lst(env->stck);
 	second = pvec_nth(env->stck, leng - 2);
 	if (second.u.num < 0)
-	    execerror(env->filename, "non-negative integer", file);
+	    execerror("non-negative integer", file);
 	switch (first.op) {
 	case LIST_  : if (!pvec_cnt(first.u.lis))
-			  execerror(env->filename, "non-empty list", file);
+			  execerror("non-empty list", file);
 		      if (second.u.num >= pvec_cnt(first.u.lis))
-			  execerror(env->filename, "smaller index", file);
+			  execerror("smaller index", file);
 		      break;
 	case STRING_:
 	case BIGNUM_: if (!*first.u.str)
-			  execerror(env->filename, "non-empty string", file);
+			  execerror("non-empty string", file);
 		      if (second.u.num >= (int)strlen(first.u.str))
-			  execerror(env->filename, "smaller index", file);
+			  execerror("smaller index", file);
 		      break;
 	case SET_   : if (!first.u.set)
-			  execerror(env->filename, "non-empty set", file);
+			  execerror("non-empty set", file);
 		      for (i = 0, j = second.u.num; i < SETSIZE; i++)
 			  if (first.u.set & ((int64_t)1 << i)) {
 			      if (!j)
 				  return;
 			      j--;
 			  }
-		      execerror(env->filename, "smaller index", file);
+		      execerror("smaller index", file);
 		      break;
-	default     : execerror(env->filename, "aggregate parameter", file); 
+	default     : execerror("aggregate parameter", file); 
 	}
 	break;
     case AT:
 	if (leng < 2)
-	    execerror(env->filename, "two parameters", file);
+	    execerror("two parameters", file);
 	first = pvec_lst(env->stck);
 	second = pvec_nth(env->stck, leng - 2);
 	if (first.u.num < 0)
-	    execerror(env->filename, "non-negative integer", file);
+	    execerror("non-negative integer", file);
 	switch (second.op) {
 	case LIST_  : if (!pvec_cnt(second.u.lis))
-			  execerror(env->filename, "non-empty list", file);
+			  execerror("non-empty list", file);
 		      if (first.u.num >= pvec_cnt(second.u.lis))
-			  execerror(env->filename, "smaller index", file);
+			  execerror("smaller index", file);
 		      break;
 	case STRING_:
 	case BIGNUM_: if (!*second.u.str)
-			  execerror(env->filename, "non-empty string", file);
+			  execerror("non-empty string", file);
 		      if (first.u.num >= (int)strlen(second.u.str))
-			  execerror(env->filename, "smaller index", file);
+			  execerror("smaller index", file);
 		      break;
 	case SET_   : if (!second.u.set)
-			  execerror(env->filename, "non-empty set", file);
+			  execerror("non-empty set", file);
 		      for (i = 0, j = first.u.num; i < SETSIZE; i++)
 			  if (second.u.set & ((int64_t)1 << i)) {
 			      if (!j)
 				  return;
 			      j--;
 			  }
-		      execerror(env->filename, "smaller index", file);
+		      execerror("smaller index", file);
 		      break;
-	default     : execerror(env->filename, "aggregate parameter", file);
+	default     : execerror("aggregate parameter", file);
 	}
 	break;
 /*
@@ -704,72 +705,71 @@ void parm(pEnv env, int num, Params type, char *file)
 */
     case DIV:
 	if (leng < 2)
-	    execerror(env->filename, "two parameters", file);
+	    execerror("two parameters", file);
 	first = pvec_lst(env->stck);
 	second = pvec_nth(env->stck, leng - 2);
 	if (first.op != INTEGER_ || second.op != INTEGER_)
-	    execerror(env->filename, "two integers", file);
+	    execerror("two integers", file);
 	if (!first.u.num)
-	    execerror(env->filename, "non-zero operand", file);
+	    execerror("non-zero operand", file);
 	break;
     case REM:
 	if (leng < 2)
-	    execerror(env->filename, "two parameters", file);
+	    execerror("two parameters", file);
 	first = pvec_lst(env->stck);
 	second = pvec_nth(env->stck, leng - 2);
 	if (first.op != FLOAT_ && first.op != INTEGER_)
-	    execerror(env->filename, "float or integer", file);
+	    execerror("float or integer", file);
 	if (second.op != FLOAT_ && second.op != INTEGER_)
-	    execerror(env->filename, "two floats or integers", file);
+	    execerror("two floats or integers", file);
 	if ((first.op == FLOAT_ && !first.u.dbl) || !first.u.num)
-	    execerror(env->filename, "non-zero operand", file);
+	    execerror("non-zero operand", file);
 	break;
     case DIVIDE:
 	if (leng < 2)
-	    execerror(env->filename, "two parameters", file);
+	    execerror("two parameters", file);
 	first = pvec_lst(env->stck);
 	second = pvec_nth(env->stck, leng - 2);
 	if (first.op != BIGNUM_ && first.op != FLOAT_ && first.op != INTEGER_)
-	    execerror(env->filename, "float or integer", file);
+	    execerror("float or integer", file);
 	if (second.op != BIGNUM_ && second.op != FLOAT_ &&
 	    second.op != INTEGER_)
-	    execerror(env->filename, "two floats or integers", file);
+	    execerror("two floats or integers", file);
 	if ((first.op == BIGNUM_ && first.u.str[1] == '0') ||
 	    (first.op == FLOAT_ && !first.u.dbl) || !first.u.num)
-	    execerror(env->filename, "non-zero divisor", file);
+	    execerror("non-zero divisor", file);
 	break;
 /*
     check numeric list:
 */
     case FWRITE:
 	if (leng < 2)
-	    execerror(env->filename, "two parameters", file);
+	    execerror("two parameters", file);
 	first = pvec_lst(env->stck);
 	second = pvec_nth(env->stck, leng - 2);
 	if (first.op != LIST_)
-	    execerror(env->filename, "list", file);
+	    execerror("list", file);
 	if (second.op != FILE_ || !second.u.fil)
-	    execerror(env->filename, "file", file);
+	    execerror("file", file);
 	for (i = pvec_cnt(first.u.lis) - 1; i >= 0; i--) {
 	    second = pvec_nth(first.u.lis, i);
 	    if (second.op != INTEGER_)
-		execerror(env->filename, "numeric list", file);
+		execerror("numeric list", file);
 	}
 	break;
 /*
  * check list at top with user defined symbol.
  */
     case ASSIGN:
-	if (leng < 2)
-	    execerror(env->filename, "two parameters", file);
+	checknum(env->filename, num, leng, file);
 	first = pvec_lst(env->stck);
 	if (first.op != LIST_)
-	    execerror(env->filename, "list", file);
+	    execerror("list", file);
 	if (!pvec_cnt(first.u.lis))
-	    execerror(env->filename, "non-empty list", file);
+	    execerror("non-empty list", file);
 	first = pvec_lst(first.u.lis);
 	if (first.op != USR_)
-	    execerror(env->filename, "user defined symbol", file);
+	    execerror("user defined symbol", file);
 	break;
 #ifdef USE_MULTI_THREADS_JOY
 /*
@@ -777,20 +777,20 @@ void parm(pEnv env, int num, Params type, char *file)
 */
     case RECEIVE:
 	if (leng < 1)
-	    execerror(env->filename, "one parameter", file);
+	    execerror("one parameter", file);
 	first = pvec_lst(env->stck);
 	if (first.op != INTEGER_)
-	    execerror(env->filename, "channel", file);
+	    execerror("channel", file);
 	break;
 /*
     channel as second parameter:
 */
     case SEND:
 	if (leng < 2)
-	    execerror(env->filename, "two parameters", file);
+	    execerror("two parameters", file);
 	second = pvec_nth(env->stck, leng - 2);
 	if (second.op != INTEGER_)
-	    execerror(env->filename, "channel", file);
+	    execerror("channel", file);
 	break;
 #endif
     }
diff --git a/prim.c b/prim.c
index c7f61c6..2db44bb 100644
--- a/prim.c
+++ b/prim.c
@@ -73,6 +73,7 @@
 #include "./src/file.c"
 #include "./src/filetime.c"
 #include "./src/filter.c"
+#include "./src/finclude.c"
 #include "./src/first.c"
 #include "./src/fjump.c"
 #include "./src/float.c"
@@ -98,7 +99,6 @@
 #include "./src/genrecaux.c"
 #include "./src/geql.c"
 #include "./src/get.c"
-#include "./src/getch.c"
 #include "./src/getenv.c"
 #include "./src/gmtime.c"
 #include "./src/greater.c"
@@ -232,6 +232,7 @@
 #include "./src/unary2.c"
 #include "./src/unary3.c"
 #include "./src/unary4.c"
+#include "./src/unassign.c"
 #include "./src/uncons.c"
 #include "./src/undeferror.c"
 #include "./src/undefs.c"
diff --git a/prim.h b/prim.h
index 4471124..5eaba41 100644
--- a/prim.h
+++ b/prim.h
@@ -73,6 +73,7 @@ void fgets_(pEnv env);
 void file_(pEnv env);
 void filetime_(pEnv env);
 void filter_(pEnv env);
+void finclude_(pEnv env);
 void first_(pEnv env);
 void fjump_(pEnv env);
 void float_(pEnv env);
@@ -98,7 +99,6 @@ void genrec_(pEnv env);
 void genrecaux_(pEnv env);
 void geql_(pEnv env);
 void get_(pEnv env);
-void getch_(pEnv env);
 void getenv_(pEnv env);
 void gmtime_(pEnv env);
 void greater_(pEnv env);
@@ -232,6 +232,7 @@ void unary_(pEnv env);
 void unary2_(pEnv env);
 void unary3_(pEnv env);
 void unary4_(pEnv env);
+void unassign_(pEnv env);
 void uncons_(pEnv env);
 void undeferror_(pEnv env);
 void undefs_(pEnv env);
diff --git a/save.c b/save.c
index 0e64c29..bd7c75d 100644
--- a/save.c
+++ b/save.c
@@ -1,7 +1,7 @@
 /*
     module  : save.c
-    version : 1.12
-    date    : 03/21/24
+    version : 1.13
+    date    : 05/06/24
 */
 #include "globals.h"
 #include "prim.h"
@@ -12,6 +12,7 @@
  */
 void save(pEnv env, NodeList *list, int num, int remove)
 {
+    FILE *fp;
     Node node;
     int status;
 
@@ -26,9 +27,17 @@ void save(pEnv env, NodeList *list, int num, int remove)
     if ((status = pvec_getarity(list)) == ARITY_UNKNOWN) {
 	status = arity(env, list, num) == 1 ? ARITY_OK : ARITY_NOT_OK;
 	if (env->overwrite) {
-	    printf("%s: (", status == ARITY_OK ? "info" : "warning");
-	    writeterm(env, list, stdout);
-	    printf(") has %scorrect arity\n", status == ARITY_OK ?  "" : "in");
+	    /*
+	     * Arities are reported in a log file, because the screen may be
+	     * cleared right after displaying a message.
+	     */
+	    if ((fp = fopen("joy.log", "a")) != 0) {
+		fprintf(fp, "%s: (", status == ARITY_OK ? "info" : "warning");
+		writeterm(env, list, fp);
+		fprintf(fp, ") has %scorrect arity\n", status == ARITY_OK ?
+			"" : "in");
+		fclose(fp);
+	    }
 	}
     }
     pvec_setarity(list, status);
diff --git a/scan.c b/scan.c
index ab8d48d..613e6f3 100644
--- a/scan.c
+++ b/scan.c
@@ -1,7 +1,7 @@
 /*
     module  : scan.c
-    version : 1.18
-    date    : 03/21/24
+    version : 1.20
+    date    : 05/02/24
 */
 #include "globals.h"
 
@@ -35,7 +35,7 @@ static void redirect(FILE *fp, char *str)
 {
     infile[ilevel].line = yylineno;	/* save last line number and line */
     if (ilevel + 1 == INPSTACKMAX)	/* increase the include level */
-	execerror(str, "fewer include files", "include");
+	execerror("fewer include files", "include");
     infile[++ilevel].fp = yyin = fp; 	/* update yyin, used by yylex */
     infile[ilevel].line = 1;		/* start with line 1 */
     strncpy(infile[ilevel].name, str, FILENAMEMAX);
@@ -120,13 +120,13 @@ void include(pEnv env, char *name)
      * If that also fails, no other path can be tried and an error is
      * generated.
      */
-    execerror(name, "valid file name", "include");
+    execerror("valid file name", "include");
 }
 
 /*
- * yywrap - continue reading after EOF.
+ * my_yywrap - continue reading after EOF.
  */
-int yywrap(void)
+int my_yywrap(pEnv env)
 {
     if (!ilevel)			/* at end of first file, end program */
 	return 1;			/* terminate */
@@ -134,6 +134,8 @@ int yywrap(void)
     infile[ilevel].fp = 0;		/* invalidate file pointer */
     yyin = infile[--ilevel].fp;		/* proceed with previous file */
     old_buffer(infile[ilevel].line);	/* and previous input buffer */
+    if (env->finclude_busy)
+	longjmp(env->finclude, 1);	/* back to finclude */
     return 0;				/* continue with old buffer */
 }
 
diff --git a/src/finclude.c b/src/finclude.c
new file mode 100644
index 0000000..99b15b5
--- /dev/null
+++ b/src/finclude.c
@@ -0,0 +1,26 @@
+/*
+    module  : finclude.c
+    version : 1.11
+    date    : 05/02/24
+*/
+#ifndef FINCLUDE_C
+#define FINCLUDE_C
+
+/**
+Q0  OK  3160  finclude  :  DU  S  ->  F ...
+[FOREIGN] Reads Joy source code from stream S and pushes it onto stack.
+*/
+void finclude_(pEnv env)
+{
+    Node node;
+
+    PARM(1, STRTOD);
+    env->stck = pvec_pop(env->stck, &node);	/* remove file name */
+    include(env, node.u.str);
+    env->finclude_busy = 1;		/* tell scanner about finclude */
+    if (setjmp(env->finclude))
+	env->finclude_busy = 0;		/* done with finclude */
+    else while (1)
+	get_(env);			/* read all factors from file */
+}
+#endif
diff --git a/src/fput.c b/src/fput.c
index 2a2d124..6a8ffed 100644
--- a/src/fput.c
+++ b/src/fput.c
@@ -1,7 +1,7 @@
 /*
     module  : fput.c
-    version : 1.9
-    date    : 03/05/24
+    version : 1.10
+    date    : 04/27/24
 */
 #ifndef FPUT_C
 #define FPUT_C
@@ -23,6 +23,5 @@ void fput_(pEnv env)
 	putc(']', node.u.fil);
     } else
 	writefactor(env, elem, node.u.fil);
-    putc(' ', node.u.fil);
 }
 #endif
diff --git a/src/getch.c b/src/getch.c
deleted file mode 100644
index 7211229..0000000
--- a/src/getch.c
+++ /dev/null
@@ -1,27 +0,0 @@
-/*
-    module  : getch.c
-    version : 1.13
-    date    : 03/21/24
-*/
-#ifndef GETCH_C
-#define GETCH_C
-
-/**
-Q0  POSTPONE  3160  getch  :  A  ->  N
-[IMPURE] Reads a character from input and puts it onto stack.
-*/
-void getch_(pEnv env)
-{
-    static unsigned char init;
-    Node node;
-
-    node.u.num = get_input();
-    if (!init) {
-	if (node.u.num == '\n')
-	    node.u.num = get_input();		/* skip first newline */
-	init = 1;
-    }
-    node.op = CHAR_;
-    env->stck = pvec_add(env->stck, node);
-}
-#endif
diff --git a/src/quit.c b/src/quit.c
index da81d3e..c66f9d9 100644
--- a/src/quit.c
+++ b/src/quit.c
@@ -1,7 +1,7 @@
 /*
     module  : quit.c
-    version : 1.12
-    date    : 03/21/24
+    version : 1.13
+    date    : 04/29/24
 */
 #ifndef QUIT_C
 #define QUIT_C
@@ -12,6 +12,6 @@ Exit from Joy.
 */
 void quit_(pEnv env)
 {
-    exit(EXIT_SUCCESS);
+    abortexecution_(ABORT_QUIT);
 }
 #endif
diff --git a/src/unassign.c b/src/unassign.c
new file mode 100644
index 0000000..d0d6bb3
--- /dev/null
+++ b/src/unassign.c
@@ -0,0 +1,28 @@
+/*
+    module  : unassign.c
+    version : 1.1
+    date    : 05/06/24
+*/
+#ifndef UNASSIGN_C
+#define UNASSIGN_C
+
+/**
+Q0  IGNORE_POP  3235  unassign  :  D  [N]  ->
+[IMPURE] Sets the body of the name N to uninitialized.
+*/
+void unassign_(pEnv env)
+{
+    Node node;
+    int index;
+    Entry ent;
+
+    PARM(1, ASSIGN);				/* quotation on top */
+    env->stck = pvec_pop(env->stck, &node);	/* singleton list */
+    node = pvec_lst(node.u.lis);		/* first/last element */
+    index = node.u.ent;				/* index user defined name */
+    ent = vec_at(env->symtab, index);		/* symbol table entry */
+    ent.is_user = 1;				/* ensure again user defined */
+    ent.u.body = 0;				/* (re)initialise body */
+    vec_at(env->symtab, index) = ent;		/* update symbol table */
+}
+#endif
diff --git a/tabl.c b/tabl.c
index 49b405a..8710561 100644
--- a/tabl.c
+++ b/tabl.c
@@ -214,7 +214,7 @@
 /* 3130 */ { Q0, IGNORE_OK, "quit", quit_, "N", "->", "Exit from Joy.\n" },
 /* 3140 */ { Q0, OK, "casting", casting_, "DDA", "X Y  ->  Z", "[EXT] Z takes the value from X and uses the value from Y as its type.\n" },
 /* 3150 */ { Q0, OK, "filetime", filetime_, "DA", "F  ->  T", "[FOREIGN] T is the modification time of file F.\n" },
-/* 3160 */ { Q0, POSTPONE, "getch", getch_, "A", "->  N", "[IMPURE] Reads a character from input and puts it onto stack.\n" },
+/* 3160 */ { Q0, OK, "finclude", finclude_, "DU", "S  ->  F ...", "[FOREIGN] Reads Joy source code from stream S and pushes it onto stack.\n" },
 /* 3170 */ { Q0, OK, "over", over_, "A", "X Y  ->  X Y X", "[EXT] Pushes an extra copy of the second item X on top of the stack.\n" },
 /* 3180 */ { Q0, OK, "pick", pick_, "DA", "X Y Z 2  ->  X Y Z X", "[EXT] Pushes an extra copy of nth (e.g. 2) item X on top of the stack.\n" },
 /* 3190 */ { Q0, IGNORE_POP, "assign", assign_, "DD", "V [N]  ->", "[IMPURE] Assigns value V to the variable with name N.\n" },
@@ -222,6 +222,7 @@
 /* 3210 */ { Q0, OK, "sametype", sametype_, "DDA", "X Y  ->  B", "[EXT] Tests whether X and Y have the same type.\n" },
 /* 3220 */ { Q0, OK, "scale", scale_, "D", "I  ->", "[NUM] Sets the number of digits to be used after the decimal point.\n" },
 /* 3230 */ { Q0, OK, "typeof", typeof_, "DA", "X  ->  I", "[EXT] Replace X by its type.\n" },
+/* 3235 */ { Q0, IGNORE_POP, "unassign", unassign_, "D", "[N]  ->", "[IMPURE] Sets the body of the name N to uninitialized.\n" },
 /* 3240 */ { Q0, OK, "exit", exit_, "N", "->", "[MTH] Exit a thread.\n" },
 /* 3250 */ { Q0, OK, "kill", kill_, "N", "->", "[MTH] Make all threads eligible for garbage collection.\n" },
 /* 3260 */ { Q0, OK, "recv", recv_, "A", "P  ->  P  N", "[MTH] Receive a node from a channel and push it on the stack.\n" },
diff --git a/test2/CMakeLists.txt b/test2/CMakeLists.txt
index 7059b3e..8213703 100644
--- a/test2/CMakeLists.txt
+++ b/test2/CMakeLists.txt
@@ -1,7 +1,7 @@
 #
 #   module  : CMakeLists.txt
-#   version : 1.12
-#   date    : 04/11/24
+#   version : 1.13
+#   date    : 05/02/24
 #
 macro(exe9 src)
 add_custom_target(${src}.out ALL
@@ -104,7 +104,6 @@ exe9(gc2)
 exe9(genrec)
 exe9(geql)
 exe9(get)
-exe9(getch)
 exe9(getenv)
 exe9(gmtime)
 exe9(greater)
diff --git a/test2/body.joy b/test2/body.joy
index 2729f91..a8523fa 100644
--- a/test2/body.joy
+++ b/test2/body.joy
@@ -1,8 +1,6 @@
 (*
     module  : body.joy
-    version : 1.4
-    date    : 03/21/24
+    version : 1.5
+    date    : 04/19/24
 *)
-DEFINE	last == dup rest null [first] [rest last] branch.
-
-[last] first body [dup rest null [first] [rest last] branch] equal.
+[sum] first body [0 [+] fold] equal.
diff --git a/test2/equal.joy b/test2/equal.joy
index 4502713..4246d1e 100644
--- a/test2/equal.joy
+++ b/test2/equal.joy
@@ -1,13 +1,11 @@
 (*
     module  : equal.joy
-    version : 1.9
-    date    : 04/11/24
+    version : 1.10
+    date    : 04/19/24
 *)
-DEFINE	last == dup rest null [first] [rest last] branch.
-
-[last] first [pop] first equal false =.
-[last] first 10 equal false =.
-[pop] first [last] first equal false =.
+[sum] first [pop] first equal false =.
+[sum] first 10 equal false =.
+[pop] first [sum] first equal false =.
 [pop] first [pop] first equal.
 [pop] first 10 equal false =.
 1 true equal.
diff --git a/test2/getch.joy b/test2/getch.joy
deleted file mode 100644
index f3c70c9..0000000
--- a/test2/getch.joy
+++ /dev/null
@@ -1,10 +0,0 @@
-(*
-    module  : getch.joy
-    version : 1.5
-    date    : 03/21/24
-*)
-0 setautoput getch getch getch.
-ABC
-1 setautoput 'C =.
-'B =.
-'A =.
diff --git a/test2/helpdetail.joy b/test2/helpdetail.joy
index c54f845..d29564a 100644
--- a/test2/helpdetail.joy
+++ b/test2/helpdetail.joy
@@ -1,12 +1,10 @@
 (*
     module  : helpdetail.joy
-    version : 1.5
-    date    : 03/22/24
+    version : 1.6
+    date    : 04/19/24
 *)
-DEFINE	last == dup rest null [first] [rest last] branch.
-
 "test" "w" fopen
-[stdin stdout stderr 3.14 [] "" {} 10 'A true maxint helpdetail last dummy]
+[stdin stdout stderr 3.14 [] "" {} 10 'A true maxint helpdetail sum dummy]
 cons helpdetail.
 $ cat test
 $ rm test
diff --git a/test2/name.joy b/test2/name.joy
index 33922e9..5bdd431 100644
--- a/test2/name.joy
+++ b/test2/name.joy
@@ -1,12 +1,10 @@
 (*
     module  : name.joy
-    version : 1.4
-    date    : 03/21/24
+    version : 1.5
+    date    : 04/19/24
 *)
-DEFINE	last == dup rest null [first] [rest last] branch.
-
 [pop] first name "pop" =.
-[last] first name "last" =.
+[sum] first name "sum" =.
 true name " truth value type" =.
 'A name " character type" =.
 10 name " integer type" =.
diff --git a/test2/null.joy b/test2/null.joy
index 0b52c28..33d4d76 100644
--- a/test2/null.joy
+++ b/test2/null.joy
@@ -1,12 +1,10 @@
 (*
     module  : null.joy
-    version : 1.4
-    date    : 03/21/24
+    version : 1.5
+    date    : 04/19/24
 *)
-DEFINE	last == dup rest null [first] [rest last] branch.
-
 [pop] first null false =.
-[last] first null false =.
+[sum] first null false =.
 false null.
 true null false =.
 '\000 null.
diff --git a/test2/put.joy b/test2/put.joy
index 1b05276..505d62a 100644
--- a/test2/put.joy
+++ b/test2/put.joy
@@ -1,12 +1,10 @@
 (*
     module  : put.joy
-    version : 1.5
-    date    : 04/15/24
+    version : 1.6
+    date    : 04/19/24
 *)
-DEFINE	last == dup rest null [first] [rest last] branch.
-
 [pop] first putln.
-[last] first putln.
+[sum] first putln.
 true putln.
 'A putln.
 10 putln.
diff --git a/test2/typeof.joy b/test2/typeof.joy
index 2b0a2ba..4dd1c1e 100644
--- a/test2/typeof.joy
+++ b/test2/typeof.joy
@@ -1,11 +1,9 @@
 (*
     module  : typeof.joy
-    version : 1.3
-    date    : 03/21/24
+    version : 1.4
+    date    : 04/19/24
 *)
-DEFINE	last == dup rest null [first] [rest last] branch.
-
-[last] first typeof 2 =.
+[sum] first typeof 2 =.
 [pop] first typeof 3 =.
 true typeof 4 =.
 'A typeof 5 =.
diff --git a/test2/user.joy b/test2/user.joy
index 4006c98..44aafc5 100644
--- a/test2/user.joy
+++ b/test2/user.joy
@@ -1,9 +1,7 @@
 (*
     module  : user.joy
-    version : 1.4
-    date    : 03/21/24
+    version : 1.5
+    date    : 04/19/24
 *)
-DEFINE	last == dup rest null [first] [rest last] branch.
-
-[last] first user.
+[sum] first user.
 [pop] first user false =.
diff --git a/writ.c b/writ.c
index 600d4ca..e2a95a9 100644
--- a/writ.c
+++ b/writ.c
@@ -1,7 +1,7 @@
 /*
  *  module  : writ.c
- *  version : 1.22
- *  date    : 04/11/24
+ *  version : 1.24
+ *  date    : 04/23/24
  */
 #include "globals.h"
 
@@ -23,7 +23,7 @@ void writefactor(pEnv env, Node node, FILE *fp)
  * only serves as a reminder for future customers.
  */
     if (!env->stck)
-	execerror(env->filename, "non-empty stack", "print");
+	execerror("non-empty stack", "print");
 #endif
     switch (node.op) {
     case USR_PRIME_:
@@ -96,9 +96,11 @@ void writefactor(pEnv env, Node node, FILE *fp)
     case FLOAT_:
 	sprintf(buf, "%g", node.u.dbl);		/* exponent character is e */
 	if ((ptr = strchr(buf, '.')) == 0) {	/* locate decimal point */
-	    if ((ptr = strchr(buf, 'e')) == 0)  /* locate start of exponent */
-		strcat(buf, ".0");		/* append decimal point + 0 */
-	    else {
+	    if ((ptr = strchr(buf, 'e')) == 0) {/* locate start of exponent */
+		i = buf[strlen(buf) - 1];
+		if (isdigit(i))			/* check digit present */
+		    strcat(buf, ".0");		/* add decimal point and 0 */
+	    } else {
 		strcpy(tmp, ptr);		/* save exponent */
 		sprintf(ptr, ".0%s", tmp);	/* insert decimal point + 0 */
 	    }
@@ -202,7 +204,7 @@ void writeterm(pEnv env, NodeList *list, FILE *fp)
 	for (i = j - 1; i >= 0; i--) {
 	    writefactor(env, pvec_nth(list, i), fp);
 	    if (i)
-		putchar(' ');
+		putc(' ', fp);
 	}
     else {
 	vec_init(array);			/* collect nodes in a vector */
@@ -217,13 +219,13 @@ void writeterm(pEnv env, NodeList *list, FILE *fp)
  */
 void writestack(pEnv env, NodeList *list, FILE *fp)
 {
-    int i, j;
+    int i;
     vector(Node) *array;
 
-    if ((j = pvec_cnt(list)) == 0)
+    if ((i = pvec_cnt(list)) == 0)
 	return;
     vec_init(array);				/* collect nodes in a vector */
-    for (i = j - 1; i >= 0; i--)
+    for (--i; i >= 0; i--)
 	vec_push(array, pvec_nth(list, i));
     writing(env, (void *)array, fp);
 }
diff --git a/xerr.c b/xerr.c
index da8e4d8..6857762 100644
--- a/xerr.c
+++ b/xerr.c
@@ -1,14 +1,14 @@
 /*
  *  module  : xerr.c
- *  version : 1.2
- *  date    : 03/21/24
+ *  version : 1.3
+ *  date    : 04/23/24
  */
 #include "globals.h"
 
 /*
     print a runtime error to stderr and abort the execution of current program.
 */
-void execerror(char *filename, char *message, char *op)
+void execerror(char *message, char *op)
 {
     int leng = 0;
     char *ptr, *str;
@@ -22,7 +22,6 @@ void execerror(char *filename, char *message, char *op)
     else
 	leng = strlen(ptr);
     fflush(stdout);
-    fprintf(stderr, "%s:run time error: %s needed for %.*s\n", filename,
-	    message, leng, ptr);
-    abortexecution_(ABORT_RETRY);
+    fprintf(stderr, "run time error: %s needed for %.*s\n", message, leng, ptr);
+    abortexecution_(ABORT_ERROR);
 }