diff --git a/eval.c b/eval.c
index a94ddcde..3e664860 100644
--- a/eval.c
+++ b/eval.c
@@ -665,10 +665,11 @@ static void generate_opcode_app (sexp app, sexp context) {
   /* maybe push the default for an optional argument */
   if ((num_args == sexp_opcode_num_args(op))
       && sexp_opcode_variadic_p(op)
-      && sexp_opcode_data(op)
-      && sexp_opcode_opt_param_p(op)) {
-    emit_push(sexp_opcode_data(op), context);
-    emit(OP_CDR, context);
+      && sexp_opcode_default(op)
+      && (sexp_opcode_class(op) != OPC_PARAMETER)) {
+    emit_push(sexp_opcode_default(op), context);
+    if (sexp_opcode_opt_param_p(op))
+      emit(OP_CDR, context);
     sexp_context_depth(context)++;
     num_args++;
   }
@@ -714,8 +715,8 @@ static void generate_opcode_app (sexp app, sexp context) {
       emit_word((sexp_uint_t)sexp_opcode_data(op), context);
     break;
   case OPC_PARAMETER:
-    emit_push(sexp_opcode_data(op), context);
-    emit(OP_CDR, context);
+    emit_push(sexp_opcode_default(op), context);
+    emit((num_args == 0 ? OP_CDR : OP_SET_CDR), context);
   default:
     emit(sexp_opcode_code(op), context);
   }
@@ -1654,10 +1655,10 @@ static sexp sexp_make_standard_env (sexp version) {
     op = &opcodes[i];
     if ((! standard_env_syms_interned_p)
         && sexp_opcode_opt_param_p(op)
-        && sexp_opcode_data(op)) {
-      sym = sexp_intern((char*)sexp_opcode_data(op));
+        && sexp_opcode_default(op)) {
+      sym = sexp_intern((char*)sexp_opcode_default(op));
       cell = env_cell_create(e, sym, SEXP_UNDEF);
-      sexp_opcode_data(op) = cell;
+      sexp_opcode_default(op) = cell;
     }
     env_define(e, sexp_intern(sexp_opcode_name(op)), op);
   }
diff --git a/init.scm b/init.scm
index 027dac98..9348286e 100644
--- a/init.scm
+++ b/init.scm
@@ -2,7 +2,6 @@
 ;; syntax-rules
 ;; number->string string->number
 ;; symbol->string string->symbol
-;; with-input-from-file with-output-to-file
 
 ;; provide c[ad]{2,4}r
 
@@ -446,6 +445,22 @@
     (close-output-port in)
     res))
 
+(define (with-input-from-file file thunk)
+  (let ((old-in (current-input-port))
+        (tmp-in (open-input-file file)))
+    (current-input-port tmp-in)
+    (let ((res (thunk)))
+      (current-input-port old-in)
+      res)))
+
+(define (with-output-to-file file thunk)
+  (let ((old-out (current-input-port))
+        (tmp-out (open-output-file file)))
+    (current-input-port tmp-out)
+    (let ((res (thunk)))
+      (current-output-port old-out)
+      res)))
+
 ;; values
 
 (define *values-tag* (list 'values))
diff --git a/opcodes.c b/opcodes.c
index f4f326b4..10347def 100644
--- a/opcodes.c
+++ b/opcodes.c
@@ -1,60 +1,63 @@
 
-#define _OP(c,o,n,m,t,u,i,s,d,p) {.tag=SEXP_OPCODE, .value={.opcode={c, o, n, m, t, u, i, s, d, p}}}
-#define _FN(o,n,t,u,s,f) _OP(OPC_FOREIGN, o, n, 0, t, u, 0, s, (sexp)f, NULL)
-#define _FN0(s, f) _FN(OP_FCALL0, 0, 0, 0, s, f)
-#define _FN1(t, s, f) _FN(OP_FCALL1, 1, t, 0, s, f)
-#define _FN2(t, u, s, f) _FN(OP_FCALL2, 2, t, u, s, f)
-#define _FN3(t, u, s, f) _FN(OP_FCALL3, 3, t, u, s, f)
-#define _FN4(t, u, s, f) _FN(OP_FCALL4, 4, t, u, s, f)
-#define _PARAM(n,a,t) _OP(OPC_PARAMETER, OP_NOOP, 0, 2, t, 0, 0, n, a, NULL)
+#define _OP(c,o,n,m,t,u,i,s,f,d) \
+  {.tag=SEXP_OPCODE,             \
+   .value={.opcode={c, o, n, m, t, u, i, s, f, d, NULL}}}
+#define _FN(o,n,m,t,u,s,f,d) _OP(OPC_FOREIGN, o, n, m, t, u, 0, s, f, (sexp)d)
+#define _FN0(s, f, d) _FN(OP_FCALL0, 0, 0, 0, 0, s, f, d)
+#define _FN1(t, s, f, d) _FN(OP_FCALL1, 1, 0, t, 0, s, f, d)
+#define _FN2(t, u, s, f, d) _FN(OP_FCALL2, 2, 0, t, u, s, f, d)
+#define _FN2OPT(t, u, s, f, d) _FN(OP_FCALL2, 1, 1, t, u, s, f, d)
+#define _FN3(t, u, s, f, d) _FN(OP_FCALL3, 3, 0, t, u, s, f, d)
+#define _FN4(t, u, s, f, d) _FN(OP_FCALL4, 4, 0, t, u, s, f, d)
+#define _PARAM(n, a, t) _OP(OPC_PARAMETER, OP_NOOP, 0, 3, t, 0, 0, n, a, 0)
 
 static struct sexp_struct opcodes[] = {
-_OP(OPC_ACCESSOR, OP_CAR, 1, 0, SEXP_PAIR, 0, 0, "car", NULL, NULL),
-_OP(OPC_ACCESSOR, OP_SET_CAR, 2, 0, SEXP_PAIR, 0, 0, "set-car!", NULL, NULL),
-_OP(OPC_ACCESSOR, OP_CDR, 1, 0, SEXP_PAIR, 0, 0, "cdr", NULL, NULL),
-_OP(OPC_ACCESSOR, OP_SET_CDR, 2, 0, SEXP_PAIR, 0, 0, "set-cdr!", NULL, NULL),
-_OP(OPC_ACCESSOR, OP_VECTOR_REF,2,0, SEXP_VECTOR, SEXP_FIXNUM, 0,"vector-ref", NULL, NULL),
-_OP(OPC_ACCESSOR, OP_VECTOR_SET,3,0, SEXP_VECTOR, SEXP_FIXNUM, 0,"vector-set!", NULL, NULL),
-_OP(OPC_ACCESSOR, OP_VECTOR_LENGTH,1,0, SEXP_VECTOR, 0, 0,"vector-length", NULL, NULL),
-_OP(OPC_ACCESSOR, OP_STRING_REF,2,0, SEXP_STRING, SEXP_FIXNUM, 0,"string-ref", NULL, NULL),
-_OP(OPC_ACCESSOR, OP_STRING_SET,3,0, SEXP_STRING, SEXP_FIXNUM, 0,"string-set!", NULL, NULL),
-_OP(OPC_ACCESSOR, OP_STRING_LENGTH,1,0, SEXP_STRING, 0, 0,"string-length", NULL, NULL),
-_OP(OPC_GENERIC, OP_FIX2FLO, 1, 0, 0, 0, 0, "exact->inexact", NULL, NULL),
-_OP(OPC_GENERIC, OP_FLO2FIX, 1, 0, 0, 0, 0, "inexact->exact", NULL, NULL),
-_OP(OPC_GENERIC, OP_CHAR2INT, 1, 0, SEXP_CHAR, 0, 0, "char->integer", NULL, NULL),
-_OP(OPC_GENERIC, OP_INT2CHAR, 1, 0, SEXP_FIXNUM, 0, 0, "integer->char", NULL, NULL),
-_OP(OPC_GENERIC, OP_CHAR_UPCASE, 1, 0, SEXP_CHAR, 0, 0, "char-upcase", NULL, NULL),
-_OP(OPC_GENERIC, OP_CHAR_DOWNCASE, 1, 0, SEXP_CHAR, 0, 0, "char-downcase", NULL, NULL),
-_OP(OPC_ARITHMETIC,     OP_ADD, 0, 1, SEXP_FIXNUM, 0, 0, "+", NULL, NULL),
-_OP(OPC_ARITHMETIC,     OP_MUL, 0, 1, SEXP_FIXNUM, 0, 0, "*", NULL, NULL),
-_OP(OPC_ARITHMETIC_INV, OP_SUB, 0, 1, SEXP_FIXNUM, 0, OP_NEGATIVE, "-", NULL, NULL),
-_OP(OPC_ARITHMETIC_INV, OP_DIV, 0, 1, SEXP_FIXNUM, 0, OP_INVERSE, "/", NULL, NULL),
-_OP(OPC_ARITHMETIC,     OP_QUOTIENT, 2, 0, SEXP_FIXNUM, SEXP_FIXNUM, 0, "quotient", NULL, NULL),
-_OP(OPC_ARITHMETIC,     OP_REMAINDER, 2, 0, SEXP_FIXNUM, SEXP_FIXNUM, 0, "remainder", NULL, NULL),
-_OP(OPC_ARITHMETIC_CMP, OP_LT,  0, 1, SEXP_FIXNUM, 0, 0, "<", NULL, NULL),
-_OP(OPC_ARITHMETIC_CMP, OP_LE,  0, 1, SEXP_FIXNUM, 0, 0, "<=", NULL, NULL),
-_OP(OPC_ARITHMETIC_CMP, OP_LT,  0, 1, SEXP_FIXNUM, 0, 1, ">", NULL, NULL),
-_OP(OPC_ARITHMETIC_CMP, OP_LE,  0, 1, SEXP_FIXNUM, 0, 1, ">=", NULL, NULL),
-_OP(OPC_ARITHMETIC_CMP, OP_EQN,  0, 1, SEXP_FIXNUM, 0, 0, "=", NULL, NULL),
-_OP(OPC_PREDICATE,      OP_EQ,  2, 0, 0, 0, 0, "eq?", NULL, NULL),
-_OP(OPC_CONSTRUCTOR,    OP_CONS, 2, 0, 0, 0, 0, "cons", NULL, NULL),
-_OP(OPC_CONSTRUCTOR,    OP_MAKE_VECTOR, 2, 0, SEXP_FIXNUM, 0, 0, "make-vector", NULL, NULL),
-_OP(OPC_CONSTRUCTOR,    OP_MAKE_PROCEDURE, 4, 0, 0, 0, 0, "make-procedure", NULL, NULL),
-_OP(OPC_TYPE_PREDICATE, OP_NULLP,  1, 0, 0, 0, 0, "null?", NULL, NULL),
-_OP(OPC_TYPE_PREDICATE, OP_EOFP,  1, 0, 0, 0, 0, "eof-object?", NULL, NULL),
-_OP(OPC_TYPE_PREDICATE, OP_SYMBOLP,  1, 0, 0, 0, 0, "symbol?", NULL, NULL),
-_OP(OPC_TYPE_PREDICATE, OP_CHARP,  1, 0, 0, 0, 0, "char?", NULL, NULL),
-_OP(OPC_TYPE_PREDICATE, OP_INTEGERP,  1, 0, 0, 0, 0, "fixnum?", NULL, NULL),
-_OP(OPC_TYPE_PREDICATE, OP_TYPEP,  1, 0, 0, 0, 0, "pair?", (sexp)SEXP_PAIR, NULL),
-_OP(OPC_TYPE_PREDICATE, OP_TYPEP,  1, 0, 0, 0, 0, "string?", (sexp)SEXP_STRING, NULL),
-_OP(OPC_TYPE_PREDICATE, OP_TYPEP,  1, 0, 0, 0, 0, "vector?", (sexp)SEXP_VECTOR, NULL),
-_OP(OPC_TYPE_PREDICATE, OP_TYPEP,  1, 0, 0, 0, 0, "flonum?", (sexp)SEXP_FLONUM, NULL),
-_OP(OPC_TYPE_PREDICATE, OP_TYPEP,  1, 0, 0, 0, 0, "procedure?", (sexp)SEXP_PROCEDURE, NULL),
-_OP(OPC_TYPE_PREDICATE, OP_TYPEP,  1, 0, 0, 0, 0, "input-port?", (sexp)SEXP_IPORT, NULL),
-_OP(OPC_TYPE_PREDICATE, OP_TYPEP,  1, 0, 0, 0, 0, "output-port?", (sexp)SEXP_OPORT, NULL),
-_OP(OPC_GENERIC, OP_APPLY1, 2, 0, SEXP_PROCEDURE, SEXP_PAIR, 0, "apply1", NULL, NULL),
-_OP(OPC_GENERIC, OP_CALLCC, 1, SEXP_PROCEDURE, 0, 0, 0, "call-with-current-continuation", NULL, NULL),
-_OP(OPC_GENERIC, OP_ERROR, 1, SEXP_STRING, 0, 0, 0, "error", NULL, NULL),
+_OP(OPC_ACCESSOR, OP_CAR, 1, 0, SEXP_PAIR, 0, 0, "car", 0, NULL),
+_OP(OPC_ACCESSOR, OP_SET_CAR, 2, 0, SEXP_PAIR, 0, 0, "set-car!", 0, NULL),
+_OP(OPC_ACCESSOR, OP_CDR, 1, 0, SEXP_PAIR, 0, 0, "cdr", 0, NULL),
+_OP(OPC_ACCESSOR, OP_SET_CDR, 2, 0, SEXP_PAIR, 0, 0, "set-cdr!", 0, NULL),
+_OP(OPC_ACCESSOR, OP_VECTOR_REF,2,0, SEXP_VECTOR, SEXP_FIXNUM, 0,"vector-ref", 0, NULL),
+_OP(OPC_ACCESSOR, OP_VECTOR_SET,3,0, SEXP_VECTOR, SEXP_FIXNUM, 0,"vector-set!", 0, NULL),
+_OP(OPC_ACCESSOR, OP_VECTOR_LENGTH,1,0, SEXP_VECTOR, 0, 0,"vector-length", 0, NULL),
+_OP(OPC_ACCESSOR, OP_STRING_REF,2,0, SEXP_STRING, SEXP_FIXNUM, 0,"string-ref", 0, NULL),
+_OP(OPC_ACCESSOR, OP_STRING_SET,3,0, SEXP_STRING, SEXP_FIXNUM, 0,"string-set!", 0, NULL),
+_OP(OPC_ACCESSOR, OP_STRING_LENGTH,1,0, SEXP_STRING, 0, 0,"string-length", 0, NULL),
+_OP(OPC_GENERIC, OP_FIX2FLO, 1, 0, 0, 0, 0, "exact->inexact", 0, NULL),
+_OP(OPC_GENERIC, OP_FLO2FIX, 1, 0, 0, 0, 0, "inexact->exact", 0, NULL),
+_OP(OPC_GENERIC, OP_CHAR2INT, 1, 0, SEXP_CHAR, 0, 0, "char->integer", 0, NULL),
+_OP(OPC_GENERIC, OP_INT2CHAR, 1, 0, SEXP_FIXNUM, 0, 0, "integer->char", 0, NULL),
+_OP(OPC_GENERIC, OP_CHAR_UPCASE, 1, 0, SEXP_CHAR, 0, 0, "char-upcase", 0, NULL),
+_OP(OPC_GENERIC, OP_CHAR_DOWNCASE, 1, 0, SEXP_CHAR, 0, 0, "char-downcase", 0, NULL),
+_OP(OPC_ARITHMETIC,     OP_ADD, 0, 1, SEXP_FIXNUM, 0, 0, "+", sexp_make_integer(0), NULL),
+_OP(OPC_ARITHMETIC,     OP_MUL, 0, 1, SEXP_FIXNUM, 0, 0, "*", sexp_make_integer(1), NULL),
+_OP(OPC_ARITHMETIC_INV, OP_SUB, 0, 1, SEXP_FIXNUM, 0, OP_NEGATIVE, "-", 0, NULL),
+_OP(OPC_ARITHMETIC_INV, OP_DIV, 0, 1, SEXP_FIXNUM, 0, OP_INVERSE, "/", 0, NULL),
+_OP(OPC_ARITHMETIC,     OP_QUOTIENT, 2, 0, SEXP_FIXNUM, SEXP_FIXNUM, 0, "quotient", 0, NULL),
+_OP(OPC_ARITHMETIC,     OP_REMAINDER, 2, 0, SEXP_FIXNUM, SEXP_FIXNUM, 0, "remainder", 0, NULL),
+_OP(OPC_ARITHMETIC_CMP, OP_LT,  0, 1, SEXP_FIXNUM, 0, 0, "<", 0, NULL),
+_OP(OPC_ARITHMETIC_CMP, OP_LE,  0, 1, SEXP_FIXNUM, 0, 0, "<=", 0, NULL),
+_OP(OPC_ARITHMETIC_CMP, OP_LT,  0, 1, SEXP_FIXNUM, 0, 1, ">", 0, NULL),
+_OP(OPC_ARITHMETIC_CMP, OP_LE,  0, 1, SEXP_FIXNUM, 0, 1, ">=", 0, NULL),
+_OP(OPC_ARITHMETIC_CMP, OP_EQN,  0, 1, SEXP_FIXNUM, 0, 0, "=", 0, NULL),
+_OP(OPC_PREDICATE,      OP_EQ,  2, 0, 0, 0, 0, "eq?", 0, NULL),
+_OP(OPC_CONSTRUCTOR,    OP_CONS, 2, 0, 0, 0, 0, "cons", 0, NULL),
+_OP(OPC_CONSTRUCTOR,    OP_MAKE_VECTOR, 1, 1, SEXP_FIXNUM, 0, 0, "make-vector", SEXP_UNDEF, NULL),
+_OP(OPC_CONSTRUCTOR,    OP_MAKE_PROCEDURE, 4, 0, 0, 0, 0, "make-procedure", 0, NULL),
+_OP(OPC_TYPE_PREDICATE, OP_NULLP,  1, 0, 0, 0, 0, "null?", 0, NULL),
+_OP(OPC_TYPE_PREDICATE, OP_EOFP,  1, 0, 0, 0, 0, "eof-object?", 0, NULL),
+_OP(OPC_TYPE_PREDICATE, OP_SYMBOLP,  1, 0, 0, 0, 0, "symbol?", 0, NULL),
+_OP(OPC_TYPE_PREDICATE, OP_CHARP,  1, 0, 0, 0, 0, "char?", 0, NULL),
+_OP(OPC_TYPE_PREDICATE, OP_INTEGERP,  1, 0, 0, 0, 0, "fixnum?", 0, NULL),
+_OP(OPC_TYPE_PREDICATE, OP_TYPEP,  1, 0, 0, 0, 0, "pair?", 0, (sexp)SEXP_PAIR),
+_OP(OPC_TYPE_PREDICATE, OP_TYPEP,  1, 0, 0, 0, 0, "string?", 0, (sexp)SEXP_STRING),
+_OP(OPC_TYPE_PREDICATE, OP_TYPEP,  1, 0, 0, 0, 0, "vector?", 0, (sexp)SEXP_VECTOR),
+_OP(OPC_TYPE_PREDICATE, OP_TYPEP,  1, 0, 0, 0, 0, "flonum?", 0, (sexp)SEXP_FLONUM),
+_OP(OPC_TYPE_PREDICATE, OP_TYPEP,  1, 0, 0, 0, 0, "procedure?", 0, (sexp)SEXP_PROCEDURE),
+_OP(OPC_TYPE_PREDICATE, OP_TYPEP,  1, 0, 0, 0, 0, "input-port?", 0, (sexp)SEXP_IPORT),
+_OP(OPC_TYPE_PREDICATE, OP_TYPEP,  1, 0, 0, 0, 0, "output-port?", 0, (sexp)SEXP_OPORT),
+_OP(OPC_GENERIC, OP_APPLY1, 2, 0, SEXP_PROCEDURE, SEXP_PAIR, 0, "apply1", 0, NULL),
+_OP(OPC_GENERIC, OP_CALLCC, 1, SEXP_PROCEDURE, 0, 0, 0, "call-with-current-continuation", 0, NULL),
+_OP(OPC_GENERIC, OP_ERROR, 1, SEXP_STRING, 0, 0, 0, "error", 0, NULL),
 _OP(OPC_IO, OP_WRITE, 1, 3, 0, SEXP_OPORT, 0, "write", (sexp)"*current-output-port*", NULL),
 _OP(OPC_IO, OP_DISPLAY, 1, 3, 0, SEXP_OPORT, 0, "display", (sexp)"*current-output-port*", NULL),
 _OP(OPC_IO, OP_WRITE_CHAR, 1, 3, 0, SEXP_OPORT, 0, "write-char", (sexp)"*current-output-port*", NULL),
@@ -64,56 +67,56 @@ _OP(OPC_IO, OP_READ, 0, 3, 0, SEXP_IPORT, 0, "read", (sexp)"*current-input-port*
 _OP(OPC_IO, OP_READ_CHAR, 0, 3, 0, SEXP_IPORT, 0, "read-char", (sexp)"*current-input-port*", NULL),
 _OP(OPC_IO, OP_PEEK_CHAR, 0, 3, 0, SEXP_IPORT, 0, "peek-char", (sexp)"*current-input-port*", NULL),
 _OP(OPC_GENERIC, OP_EVAL, 1, 3, 0, 0, 0, "eval", (sexp)"*interaction-environment*", NULL),
-_FN2(0, 0, "equal?", sexp_equalp),
-_FN1(0, "list?", sexp_listp),
-_FN1(0, "identifier?", sexp_identifierp),
-_FN4(0, SEXP_ENV, "identifier=?", sexp_identifier_eq),
-_FN1(SEXP_PAIR, "length", sexp_length),
-_FN1(SEXP_PAIR, "reverse", sexp_reverse),
-_FN1(SEXP_PAIR, "list->vector", sexp_list_to_vector),
-_FN1(SEXP_STRING, "open-input-file", sexp_open_input_file),
-_FN1(SEXP_STRING, "open-output-file", sexp_open_output_file),
-_FN1(SEXP_IPORT, "close-input-port", sexp_close_port),
-_FN1(SEXP_OPORT, "close-output-port", sexp_close_port),
-_FN1(SEXP_FIXNUM, "null-environment", sexp_make_null_env),
-_FN1(SEXP_FIXNUM, "scheme-report-environment", sexp_make_standard_env),
-_FN2(0, SEXP_ENV, "%load", sexp_load),
-_FN2(SEXP_FIXNUM, SEXP_CHAR, "make-string", sexp_make_string),
-_FN2(SEXP_STRING, SEXP_STRING, "string-cmp", sexp_string_cmp),
-_FN2(SEXP_STRING, SEXP_STRING, "string-cmp-ci", sexp_string_cmp_ci),
-_FN3(SEXP_STRING, SEXP_FIXNUM, "substring", sexp_substring),
-_FN1(SEXP_PAIR, "string-concatenate", sexp_string_concatenate),
-_FN2(0, SEXP_PAIR, "memq", sexp_memq),
-_FN2(0, SEXP_PAIR, "assq", sexp_assq),
-_FN3(SEXP_ENV, SEXP_PAIR, "make-syntactic-closure", sexp_make_synclo),
+_FN2(0, 0, "equal?", 0, sexp_equalp),
+_FN1(0, "list?", 0, sexp_listp),
+_FN1(0, "identifier?", 0, sexp_identifierp),
+_FN4(0, SEXP_ENV, "identifier=?", 0, sexp_identifier_eq),
+_FN1(SEXP_PAIR, "length", 0, sexp_length),
+_FN1(SEXP_PAIR, "reverse", 0, sexp_reverse),
+_FN1(SEXP_PAIR, "list->vector", 0, sexp_list_to_vector),
+_FN1(SEXP_STRING, "open-input-file", 0, sexp_open_input_file),
+_FN1(SEXP_STRING, "open-output-file", 0, sexp_open_output_file),
+_FN1(SEXP_IPORT, "close-input-port", 0, sexp_close_port),
+_FN1(SEXP_OPORT, "close-output-port", 0, sexp_close_port),
+_FN1(SEXP_FIXNUM, "null-environment", 0, sexp_make_null_env),
+_FN1(SEXP_FIXNUM, "scheme-report-environment", 0, sexp_make_standard_env),
+_FN2(SEXP_STRING, SEXP_ENV, "%load", 0, sexp_load),
+_FN2OPT(SEXP_FIXNUM, SEXP_CHAR, "make-string", sexp_make_character(' '), sexp_make_string),
+_FN2(SEXP_STRING, SEXP_STRING, "string-cmp", 0, sexp_string_cmp),
+_FN2(SEXP_STRING, SEXP_STRING, "string-cmp-ci", 0, sexp_string_cmp_ci),
+_FN3(SEXP_STRING, SEXP_FIXNUM, "substring", 0, sexp_substring),
+_FN1(SEXP_PAIR, "string-concatenate", 0, sexp_string_concatenate),
+_FN2(0, SEXP_PAIR, "memq", 0, sexp_memq),
+_FN2(0, SEXP_PAIR, "assq", 0, sexp_assq),
+_FN3(SEXP_ENV, SEXP_PAIR, "make-syntactic-closure", 0, sexp_make_synclo),
 _PARAM("current-input-port", (sexp)"*current-input-port*", SEXP_IPORT),
 _PARAM("current-output-port", (sexp)"*current-output-port*", SEXP_OPORT),
 _PARAM("current-error-port", (sexp)"*current-error-port*", SEXP_OPORT),
 _PARAM("current-error-handler", (sexp)"*current-error-handler*", SEXP_PROCEDURE),
 _PARAM("interaction-environment", (sexp)"*interaction-environment*", SEXP_ENV),
 #if USE_MATH
-_FN1(0, "exp", sexp_exp),
-_FN1(0, "log", sexp_log),
-_FN1(0, "sin", sexp_sin),
-_FN1(0, "cos", sexp_cos),
-_FN1(0, "tan", sexp_tan),
-_FN1(0, "asin", sexp_asin),
-_FN1(0, "acos", sexp_acos),
-_FN1(0, "atan", sexp_atan),
-_FN1(0, "sqrt", sexp_sqrt),
-_FN1(0, "round", sexp_round),
-_FN1(0, "truncate", sexp_trunc),
-_FN1(0, "floor", sexp_floor),
-_FN1(0, "ceiling", sexp_ceiling),
-_FN2(0, 0, "expt", sexp_expt),
+_FN1(0, "exp", 0, sexp_exp),
+_FN1(0, "log", 0, sexp_log),
+_FN1(0, "sin", 0, sexp_sin),
+_FN1(0, "cos", 0, sexp_cos),
+_FN1(0, "tan", 0, sexp_tan),
+_FN1(0, "asin", 0, sexp_asin),
+_FN1(0, "acos", 0, sexp_acos),
+_FN1(0, "atan", 0, sexp_atan),
+_FN1(0, "sqrt", 0, sexp_sqrt),
+_FN1(0, "round", 0, sexp_round),
+_FN1(0, "truncate", 0, sexp_trunc),
+_FN1(0, "floor", 0, sexp_floor),
+_FN1(0, "ceiling", 0, sexp_ceiling),
+_FN2(0, 0, "expt", 0, sexp_expt),
 #endif
 #if USE_STRING_STREAMS
-_FN0("open-output-string", sexp_make_output_string_port),
-_FN1(SEXP_STRING, "open-input-string", sexp_make_input_string_port),
-_FN1(SEXP_OPORT, "get-output-string", sexp_get_output_string),
+_FN0("open-output-string", 0, sexp_make_output_string_port),
+_FN1(SEXP_STRING, "open-input-string", 0, sexp_make_input_string_port),
+_FN1(SEXP_OPORT, "get-output-string", 0, sexp_get_output_string),
 #endif
 #if USE_DEBUG
-_FN2(SEXP_PROCEDURE, SEXP_OPORT, "disasm", sexp_disasm),
+_FN2(SEXP_PROCEDURE, SEXP_OPORT, "disasm", 0, sexp_disasm),
 #endif
 };
 
diff --git a/sexp.h b/sexp.h
index ae4835b2..b9e820f2 100644
--- a/sexp.h
+++ b/sexp.h
@@ -132,7 +132,7 @@ struct sexp_struct {
       unsigned char op_class, code, num_args, flags,
         arg1_type, arg2_type, inverse;
       char *name;
-      sexp data, proc;
+      sexp dflt, data, proc;
     } opcode;
     struct {
       char code;
@@ -301,6 +301,7 @@ struct sexp_struct {
 #define sexp_opcode_arg2_type(x)  ((x)->value.opcode.arg2_type)
 #define sexp_opcode_inverse(x)    ((x)->value.opcode.inverse)
 #define sexp_opcode_name(x)       ((x)->value.opcode.name)
+#define sexp_opcode_default(x)    ((x)->value.opcode.dflt)
 #define sexp_opcode_data(x)       ((x)->value.opcode.data)
 #define sexp_opcode_proc(x)       ((x)->value.opcode.proc)