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

@@ -179,11 +179,15 @@ static void enclose(Format *f, Binding *binding, const char *sep) {
 	if (binding != NULL) {
 		Binding *next = binding->next;
 		enclose(f, next, ";");
+#if !ABRIDGE_CLOSURES
+		fmtprint(f, "%S%s", binding->name, sep);
+#else
 		fmtprint(f, "%S=%#L%s", binding->name, binding->defn, " ", sep);
+#endif
 	}
 }
 
-#if 0
+#if ABRIDGE_CLOSURES
 typedef struct Chain Chain;
 struct Chain {
 	Closure *closure;
@@ -199,7 +203,7 @@ static Boolean Cconv(Format *f) {
 	Binding *binding = closure->binding;
 	Boolean altform = (f->flags & FMT_altform) != 0;
 
-#if 0
+#if ABRIDGE_CLOSURES
 	int i;
 	Chain me, *cp;
 	assert(tree->kind == nThunk || tree->kind == nLambda || tree->kind == nPrim);
@@ -226,7 +230,7 @@ static Boolean Cconv(Format *f) {
 		fmtprint(f, "%T", tree);
 	}
 
-#if 0
+#if ABRIDGE_CLOSURES
 	chain = chain->next;	/* TODO: exception unwinding? */
 #endif
 	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