Haskell's algebraic data types

Question

I\'m trying to fully understand all of Haskell\'s concepts.

In what ways are algebraic data types similar to generic types, e.g., in C# and Java? And how are they di

Answer 1

@Timbo:

You are basically right about it being sort of like an abstract Tree class with three derived classes (Empty, Leaf, and Node), but you would also need to enforce the guarantee that some one using your Tree class can never add any new derived classes, since the strategy for using the Tree datat type is to write code that switches at runtime based on the type of each element in the tree (and adding new derived types would break existing code). You can sort of imagine this getting nasty in C# or C++, but in Haskell, ML, and OCaml, this is central to the language design and syntax so coding style supports it in a much more convenient manner, via pattern matching.

ADT (sum types) are also sort of like tagged unions or variant types in C or C++.