Random numbers

[Jan Krynicky]

> Subject: Re: Random numbers
> From: Torsten Will <itwill@TechFak.Uni-Bielefeld.DE>
> 
> Hello,
> 
> > How I get a random number in Clean?
> 
> In a purely functional language it is impossible to get real random
> numbers. But there are two possibilies to solve this problem:
> 
> 1. Use a unique type for a random-generating function, but I don`t
>    know how to do this.
> 
> 2. For some problems it is enough to generate pseudo-random numbers
>    (numbers that SEEMS to be random, but are reproducable).
>    In MIRANDA I write a function like that:
> 
> //////////////  Very simple program for generating pseudo random numbers
> // Miranda-script
> // pseudoRands gives a list of pseudo-randoms between 1..10
> 
> startvalue :: num                // num is like 'int' in C
> startvalue = 42
> 
The problem is here, where to get the initial state ?
I'd need a little help from Clean.

// Something like 
getIniState::*WORLD -> (Int,*WORLD)
// would be sufficient.

> 
> Tschau, Torsten.
> 

As someone wrote in comp.lang.functional, this explicit state passing
style is sometimes making it too linear.

The best for applications I don't need the 'pseudo-random' features
would be something like a standard function (variable).
:   rand::Rand   // not unique!
and 
:   instance toReal Rand
:   instance toInt  Rand
...
where the rand would be weird in that, that it would be evaluated to
different real/int/... numbers.

But it can (I think) be done only by the developers of the compiler.

\v Cau, Jenda