close output file after write

TDL.go

@@ -26,7 +26,7 @@ func checkUsage(debugFlag string, args []string) {
 	}
 }
 
-func outfile(infile string) io.Writer {
+func outfile(infile string) *os.File {
 	basename := path.Base(infile)
 	extension := path.Ext(basename)
 	basename = strings.TrimSuffix(basename, extension)
@@ -67,7 +67,9 @@ func main() {
 			if stdout {
 				writer = os.Stdout
 			} else {
-				writer = outfile(filename)
+				out := outfile(filename)
+				defer out.Close()
+				writer = out
 			}
 			generator := NewStdGenerator(writer)
 			generator.Generate(parsed)