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## Re: [Axiom-developer] Question concerning types...

 From: Ralf Hemmecke Subject: Re: [Axiom-developer] Question concerning types... Date: Sun, 17 Sep 2006 01:43:20 +0200 User-agent: Thunderbird 1.5.0.5 (X11/20060719)

```Hi

On 09/16/2006 11:19 PM, Martin Rubey wrote:
```
```C Y <address@hidden> writes:

```
```(1) -> Q == Quaternion Fraction Integer;
```
```
Oh, I feared that this would cause trouble...

```
```in Axiom:

Q ==> Quaternion Fraction Integer;
```
```
```
Well that should work, but actually I used Aldor syntax. In Axiom you would have to write
```
Q := Quaternion Fraction Integer;

But note then Q is a variable and could change so if you then say

P := Polynomial Q
p1: P := 1
Q := Integer
p2: P := 1

```
can you assure that p1=p2? Note, the have the same type P which is Polynomial Q. Or will p1 become invalid by assigning Integer to Q?
```
```
Well, typing that into Axiom will surely reveal the answer, but could you say without doing it?
```
Oh, I just realised some weakness of Axiom...

P := Polynomial

Although Polynomial is the name of a constructor, a full type must
be specified in the context you have used it. Issue )show

Seems that not everything is first class... :-(

```
```(2) -> m(a1: Q, a2: Q, a3: Q, a4: Q): Matrix Q := matrix[[a1,a2],[a3,a4]];
```
```
```
```in Axiom and in Aldor:
```
```
```
```m(a1: Q, a2: Q, a3: Q, a4: Q): Matrix Q == matrix[[a1,a2],[a3,a4]];
```
```
Oh yes, thank you Martin, that was a stupid mistake of mine.

Ralf

```