[Oberon] Functional programming and Oberon

[Richard Hable]

Am 2016-12-14 um 18:47 schrieb Srinivas Nayak:

> But only thing we need is: a way to preserve dynamic state of a
> procedure and unnamed procedures!

In other words: closures. And the syntax better be concise, because
functional programmers use them a lot.

> What else?

Some other important features are missing for (pure / value oriented)
functional programming:

- conditional expressions

x: Integer := IF some condition THEN 42 ELSE 4711;

Conditional expressions in Oberon can not return values, so we need
mutable state (variables) for even the simplest calculations.

- local definitions of values and functions

LET x := ... IN <some expression using x>

Otherwise, we end up with a lot of very small procedure definitions or
very complex expressions.

- generics

Linked List [T] = RECORD head: T; tail: List [T] END;

Without generics (i.e. type parameters for functions, types, and values)
it is not possible to define reusable persistent collections. We can't
just build and manipulate aribitrary pointer structures.

As I have already mentioned on this list, my own attempt at creating
such a programming language can be seen here: http://trankvila.org

Richard