Abridge closure strings by default

A new 'ABRIDGE_CLOSURES' configuration parameter has been added to
esconfig.h.
It defaults to 0 so a closure string is abridged to

	%closure(a;b;...)@ * {...}

When 'ABRIDGE_CLOSURES' is enabled, some old code that was previously
commented out has been uncommented, so even closures with cyclical
references can be printed:

	; whatis <={@ x y { (x y) = @ cmd { $cmd $y } 1 ; result $x }}
	%closure(x='0 $&nestedbinding';y=1)@ cmd{$cmd $y}
	# 0 $&nestedbinding
	#	the code tree associated with the closure, i.e.
	#	'@ cmd{$cmd $y}' in this case
	# {n} $&nestedbinding
	#	the code tree bound to another closure
	#
	# NOTE: $&nestedbinding doesn't actually exist.
	#       It's purely an indicator of a cyclical reference, like
	#	how 'wryun#1=(a b . wryun#1#)' is used in some Lisps to avoid
	#	printing an endless stream of 'a b'.

conv.c

@@ -9,12 +9,18 @@ static Boolean Lconv(Format *f) {
 	List *lp, *next;
 	char *sep;
 	const char *fmt = (f->flags & FMT_altform) ? "%S%s" : "%s%s";
+	const char *arg;
 
 	lp = va_arg(f->args, List *);
 	sep = va_arg(f->args, char *);
 	for (; lp != NULL; lp = next) {
+		Closure *closure = getclosure(lp->term);
 		next = lp->next;
-		fmtprint(f, fmt, getstr(lp->term), next == NULL ? "" : sep);
+		if (closure == NULL)
+			arg = getstr(lp->term);
+		else
+			arg = str((f->flags & FMT_zeropad) ? "%0C" : "%C", closure);
+		fmtprint(f, fmt, arg, next == NULL ? "" : sep);
 	}
 	return FALSE;
 }
@@ -178,28 +184,33 @@ static Boolean Tconv(Format *f) {
 static void enclose(Format *f, Binding *binding, const char *sep) {
 	if (binding != NULL) {
 		Binding *next = binding->next;
+		long flags = f->flags;
 		enclose(f, next, ";");
-		fmtprint(f, "%S=%#L%s", binding->name, binding->defn, " ", sep);
+#if ABRIDGE_CLOSURES
+		if (flags & FMT_zeropad)
+			fmtprint(f, "%S%s", binding->name, sep);
+		else
+#endif
+			fmtprint(f, "%S=%#L%s", binding->name, binding->defn, " ", sep);
 	}
 }
 
-#if 0
 typedef struct Chain Chain;
 struct Chain {
 	Closure *closure;
 	Chain *next;
 };
 static Chain *chain = NULL;
-#endif
 
 /* %C -- print a closure */
 static Boolean Cconv(Format *f) {
 	Closure *closure = va_arg(f->args, Closure *);
 	Tree *tree = closure->tree;
 	Binding *binding = closure->binding;
 	Boolean altform = (f->flags & FMT_altform) != 0;
+	Boolean abridgec = (f->flags & FMT_zeropad) != 0;
 
-#if 0
+if (!abridgec) {
 	int i;
 	Chain me, *cp;
 	assert(tree->kind == nThunk || tree->kind == nLambda || tree->kind == nPrim);
@@ -213,22 +224,23 @@ static Boolean Cconv(Format *f) {
 	me.closure = closure;
 	me.next = chain;
 	chain = &me;
-#endif
+}
 
 	if (altform)
-		fmtprint(f, "%S", str("%C", closure));
+		fmtprint(f, "%S", str(abridgec ? "%0C" : "%C", closure));
 	else {
 		if (binding != NULL) {
+			long flags = f->flags;
 			fmtprint(f, "%%closure(");
+			f->flags = flags;
 			enclose(f, binding, "");
 			fmtprint(f, ")");
 		}
 		fmtprint(f, "%T", tree);
 	}
 
-#if 0
-	chain = chain->next;	/* TODO: exception unwinding? */
-#endif
+	if (!abridgec)
+		chain = chain->next;	/* TODO: exception unwinding? */
 	return FALSE;
 }
 

esconfig.h

@@ -15,6 +15,13 @@
  *	line definitions.  (That is, remember to do the #ifndef dance.)
  *
  *
+ *	ABRIDGE_CLOSURES
+ *		if on, produce closure strings without the values bound in a closure:
+ *			%closure(x;y;x)@ * {...}
+ *		else:
+ *			%closure(x=1;y=4;x=9)@ * {...}
+ *		this is particularly useful when dealing with "nested bindings".
+ *
  *	ASSERTIONS
  *		if this is on, asserts will be checked, raising errors on
  *		actual assertion failure.
@@ -276,6 +283,10 @@
  * default defaults -- don't change this section
  */
 
+#ifndef	ABRIDGE_CLOSURES
+#define	ABRIDGE_CLOSURES	1
+#endif
+
 #ifndef	ASSERTIONS
 #define	ASSERTIONS		1
 #endif

prim-etc.c

@@ -18,7 +18,11 @@ PRIM(echo) {
 		} else if (termeq(list->term, "--"))
 			list = list->next;
 	}
+#if ABRIDGE_CLOSURES
+	print("%0L%s", list, " ", eol);
+#else
 	print("%L%s", list, " ", eol);
+#endif
 	return true;
 }