[racket] Void expression found

From: Jos Koot (jos.koot at gmail.com)
Date: Mon Jan 5 17:20:54 EST 2015

Void is a peculiar thing.
It is used by Racket where no result is ment.
But every expression must have a (multiple) value (if it computes in finite
time)
Because the value of (void) has to be considered to be the absence of a
value,
the repl and the interactions window do not show them. For example in the
interactions window:

(void) -> no response
(write (void)) writes '#<void>'.

It seems difficult to represent the absence of a value.
Why not returing the value of (values)?
A problem, because in many cases where no value matters, Racket does require
a value.

The absence of a value in may cases is a value, namely the value of (void).
Where you use (values) in many cases problems arise.

Off topic:
For me the unanswered question remains:
Does the vacuum exist or does it not exist?
I don't know.

Jos

-----Original Message-----
From: users [mailto:users-bounces at racket-lang.org] On Behalf Of Hendrik Boom
Sent: 05 January 2015 19:24
To: racket users list
Subject: [racket] Void expression found

On Sun, Jan 04, 2015 at 11:25:52PM -0500, Alexander D. Knauth wrote:
> will (void) not work?

Only if you know it exists.

Thank you.  Every language has a few essential trivia that are hard to find
in the documentation.  Eventually you learn how the documentation is
organised and you can find them easily (in case you forget them), but until
then ...

-- hendrik
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