start improving ++

Author: jcupitt

TODO

@@ -3,10 +3,39 @@
 	print
 	++
 
-  both seemt to be strict, so eg. "join_sep ", " (map print primes)" never
-  returns, "print primes" never returns
+  try:
 
-- finish new test_snip.def
+	join_sep ", " [1..]
+	print primes
+
+  neither ever prints anything, even in the GUI
+
+- ++ implementation
+
+	LHS is MANAGEDSTRING
+
+		build a list of the right length, set last node to be RHS
+		(not [])
+
+	eval LHS to find (a:x) node
+
+		set out to be (a:(x ++ RHS))
+
+	otherwise, error
+
+  code now:
+
+	action_proc_join() calls action_proc_join_sub() for (list ++ list)
+
+	in turn, calls heap_list_cat()
+
+	that uses reduce_clone_list() to clonce the LHS, then replaces elist
+	with RHS
+
+	clone_list uses reduce_map_list(), which does eg. expanding
+	MANAGEDSTRING
+
+- makeing print lazy would probably be hard
 
 - add multiple definitions, finish function argument destructuring
 

src/action.c

@@ -812,6 +812,31 @@ static void *
 action_proc_join_sub(Reduce *rc, PElement *pe,
 	PElement *a, PElement *b, PElement *out)
 {
+	if (PEISMANAGEDSTRING(a)) {
+		PElement tail;
+
+		// expand the static string into a list
+		reduce_clone_list(rc, a, pe);
+		PEPUTPE(&tail, b);
+	}
+	else if (PEISELIST(a)) {
+	}
+	else if (PEISNODE(a) && PEGETVAL(a)->type == TAG_CONS) {
+		HeapNode *cons = PEGETVAL(a);
+		PElement hd;
+		PEPOINTLEFT(hn, &hd);
+		PElement tl;
+		PEPOINTRIGHT(hn, &tl);
+
+		PElement t;
+		if (!heap_list_add(rc->heap, &tl, &t))
+			reduce_throw(rc);
+		PEPUTP(&t,
+	}
+	else
+		g_assert(FALSE);
+
+
 	if (!heap_list_cat(rc, a, b, pe))
 		return a;