new type LinkedList, preliminary implementation

kern/formatter.go

@@ -4,7 +4,10 @@
 // formatter.go
 package kern
 
-import "fmt"
+import (
+	"fmt"
+	"strings"
+)
 
 type FmtOpt uint32 // lower 16 bits hold a bit-mask, higher 16 bits hold an indentation number
 
@@ -46,6 +49,18 @@ type Formatter interface {
 	ToString(options FmtOpt) string
 }
 
+func Format(sb *strings.Builder, item any, opt FmtOpt) {
+	if s, ok := item.(string); ok {
+		sb.WriteByte('"')
+		sb.WriteString(s)
+		sb.WriteByte('"')
+	} else if formatter, ok := item.(Formatter); ok {
+		sb.WriteString(formatter.ToString(opt))
+	} else {
+		fmt.Fprintf(sb, "%v", item)
+	}
+}
+
 func GetFormatted(v any, opt FmtOpt) (text string) {
 	if v == nil {
 		text = "(nil)"