diff --git a/src/argument_parser.ads b/src/argument_parser.ads
index 0dd250b..b847041 100644
--- a/src/argument_parser.ads
+++ b/src/argument_parser.ads
@@ -1,10 +1,10 @@
+with Ada.Strings.Unbounded; use Ada.Strings.Unbounded;
+
 package Argument_Parser is
 
    type Option is interface;
 
-   function Parse (I : string) return Option is abstract;
-
-   type Argument_Parser is tagged private;
+   function Parse (I : String) return Option is abstract;
 
    procedure Add_Positional (
       Parser : in out Argument_Parser;
@@ -15,7 +15,7 @@ package Argument_Parser is
    procedure Add_Boolean_Option (
       Parser : in out Argument_Parser;
       Short_String : string;
-      Long_String : string)
+      Long_String : string);
 
    procedure Add_Count_Option (
       Parser : in out Argument_Parser;
@@ -29,6 +29,30 @@ package Argument_Parser is
       Short_String : string;
       Long_String : string);
 
+   type String_Option is new Option with
+      record
+         Value : Unbounded_String;
+      end record;
+
+   overriding
+   function Parse (I : String) return String_Option;
+
+   type Integer_Option is new Option with
+      record
+         Value : Integer;
+      end record;
+
+   overriding
+   function Parse (I : String) return Integer_Option;
+
+   type Float_Option is new Option with
+      record
+         Value : Float;
+      end record;
+
+   overriding
+   function Parse (I : String) return Float_Option;
+
 private
 
    type Argument_Parser is tagged null record;