# Aldor

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For the Middle-earth character, see Aldor (Middle-earth).
Aldor
Paradigm multi-paradigm: object-oriented, functional, imperative, dependent typed, logic programming
Designed by Richard Dimick Jenks, Barry Trager, Stephen Watt, James Davenport, Robert Sutor, Scott Morrison
Developer IBM Thomas J. Watson Research Center
Platform Axiom computer algebra system
License Apache License
.al, .as

Aldor is a programming language. It is the successor of A# as the extension language of the Axiom computer algebra system.

The Aldor language combines imperative, functional, and object-oriented features. It has an elaborate type system[citation needed], allowing types to be used as first-class values. Aldor's syntax is heavily influenced by Pascal, but it is optionally indentation-sensitive, like Python. In its current implementation, it is compiled, but an interactive listener is provided.

Aldor is Free software, available under the Apache License.

## Examples

The Hello world program looks like this:

```#include "aldor"
#include "aldorio"

stdout << "Hello, world!" << newline;
```

Example of dependent types (from the User Guide):

```#include "aldor"
#include "aldorio"
#pile

sumlist(R: ArithmeticType, l: List R): R ==
s: R := 0;
for x in l repeat s := s + x
s

import from List Integer, Integer, List SingleFloat, SingleFloat
stdout << sumlist(Integer, [2,3,4,5]) << newline
stdout << sumlist(SingleFloat, [2.0, 2.1, 2.2, 2.4]) << newline
```
99 Bottles of Beer
```#include "aldor"
#include "aldorio"

import from Integer, String;

bob(n: Integer): String == {
b: String := " bottle";

if n ~= 1 then b := b + "s";
b + " of beer";
}

main(): () == {
n: Integer := 99;
otw: String := " on the wall";

-- refrain
while n > 0 repeat {
stdout << n << bob(n) << otw << ", " << n << bob(n) << "." << newline;
stdout << "Take one down and pass it around, ";
n := n - 1;
if n > 0 then stdout << n;
else stdout << "no more";
stdout << bob(n) << otw << "." << newline;
stdout << newline;
}

-- last verse
stdout << "No more" << bob(n) << otw << ", no more" << bob(n) << "." << newline;
stdout << "Go to the store and buy some more, ";
n: Integer := 99;
stdout << n << bob(n) << otw << "." << newline;
}

main();
```