diff --git a/flags/flags.go b/flags/flags.go
index 5e40ae8..8bc1846 100644
--- a/flags/flags.go
+++ b/flags/flags.go
@@ -10,18 +10,16 @@ type Arg struct {
 	Help string
 }
 
-type Flag struct {
-	Long  string
-	Short string
-	Val   string
-	Help  string
+// type constraint
+type Val interface {
+	string | bool
 }
 
-// there's got to be a way to generalize the val field to string|bool
-type FlagBool struct {
+// with generic Val field, instantiate like Flag[string]
+type Flag[V Val] struct {
 	Long  string
 	Short string
-	Val   bool
+	Val   V
 	Help  string
 }
 
diff --git a/go b/go
new file mode 100755
index 0000000..7a363ee
Binary files /dev/null and b/go differ
diff --git a/tag/tag.go b/tag/tag.go
index 3ef2534..231956c 100644
--- a/tag/tag.go
+++ b/tag/tag.go
@@ -8,15 +8,15 @@ import (
 
 type options struct {
 	query  flags.Arg
-	date   flags.Flag
-	invert flags.FlagBool
+	date   flags.Flag[string]
+	invert flags.Flag[bool]
 }
 
 func InitOpts() options {
 	return options{
 		flags.Arg{"", "tag query"},
-		flags.Flag{"--date", "-d", "", "date range"},
-		flags.FlagBool{"--invert", "-i", false, "invert match"},
+		flags.Flag[string]{"--date", "-d", "", "date range"},
+		flags.Flag[bool]{"--invert", "-i", false, "invert match"},
 	}
 }
 
@@ -25,14 +25,14 @@ func ParseArgs(args []string) options {
 	if len(args) == 0 {
 		return opts
 	}
-	if flags.HasDashPrefix(args[0]) {
+	if !flags.HasDashPrefix(args[0]) {
 		opts.query.Val = args[0]
 	}
 	for i, arg := range args {
 		switch arg {
 		case opts.invert.Long, opts.invert.Short:
 			opts.invert.Val = true
-		case opts.date.Long:
+		case opts.date.Long, opts.date.Short:
 			if flags.MissingValueArg(args, i) {
 				flags.HelpMissingVal(arg)
 				break