Re: Recursive algebraic data types

[gautier_niouzes@hotmail.com]

> for definition: please have a look at https://en.wikipedia.org/wiki/Recursive_data_type

"In computer programming languages, a recursive data type (also known as a recursively-defined, inductively-defined or inductive data type) is a data type for values that may contain other values of the same type."

The definition given above is nonsensical: either the data type is empty or infinitely large...

In the examples given (List), the type names can mean either a pointer to the real data, or the data itself (a list's node in that case). Clearly they are playing with words there: a node doesn't really contain the next node, but a pointer (or a reference) to the next node. So it's not really recursive, only in appearance. They play with a shortcut notation.