* [[!wikipedia Tagged union]]
* [[!wikipedia Algebraic data type]]
+* [[!wikipedia Recursive data type]]
* [[!wikipedia Pattern matching]]
* [[!wikipedia Unit type]]
* [[!wikipedia Bottom type]]
* [Type Theory](http://plato.stanford.edu/entries/type-theory/) at the Stanford Encyclopedia of Philosophy
* [Church's Type Theory](http://plato.stanford.edu/entries/type-theory-church/) at the Stanford Encyclopedia of Philosophy
* The [[!wikipedia Curry-Howard isomorphism]]
-* [The Curry-Howard correspondence in Haskell](http://www.thenewsh.com/~newsham/formal/curryhoward/)<p>
+* [The Curry-Howard correspondence in Haskell](http://www.thenewsh.com/~newsham/formal/curryhoward/)
+* [The Curry-Howard Isomorphism](http://en.wikibooks.org/wiki/Haskell/The_Curry-Howard_isomorphism) at Haskell wiki<p>
* [[!wikipedia Type polymorphism]]
* [[!wikipedia System F]]