Merge pull request #2285 from MorayJ/types

Types

doc/Language/typesystem.pod6

@@ -795,7 +795,10 @@ as a value.
 
 =head2 C<module>
 
-TODO
+Modules are usually one or more source files that expose Perl 6 constructs, such as classes, roles, grammars, subroutines and variables.
+Modules are usually used for distributing Perl 6 code as libraries which can be used in another Perl 6 programme.
+
+For a full explanation see L<Modules|/language/modules>.
 
 =head3 Versioning and authorship
 
@@ -810,11 +813,15 @@ C<.^ver> and C<^.auth>.
 
 =head2 C<package>
 
-TODO
+Packages are nested namespaces of named program elements. Modules, classes and grammars are all types of package.
+
+For a full explanation see L<Packages|/language/packages>.
 
 =head2 C<grammar>
 
-TODO
+Grammars are a specific type of class intended for parsing text. Grammars are composed of rules, tokens and regexes which are actually methods, since grammars are classes.
+
+For a full explanation see L<Grammars|/language/grammars>.
 
 =head3 Versioning and authorship