[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Chicken-users] how to unintern a symbol

From: Peter Bex
Subject: Re: [Chicken-users] how to unintern a symbol
Date: Mon, 2 Feb 2015 20:11:20 +0100
User-agent: Mutt/1.5.21 (2010-09-15)

On Mon, Feb 02, 2015 at 11:55:12AM -0700, Alexej Magura wrote:
> AFAICT that just defines a symbol to itself, and only then if you run:
> (define foo 1)
> (define foo (unintern 'foo))
> (eq? foo |foo|) => #t
> But, as I said, that only defines 'foo as |foo|: it doesn't
> /undefine/ the symbol, and it needs to have side-effects, since the
> CL /unintern/ AFAIK effects the targeted package, or in our case
> module.
> After uninterning /foo/, if I were to enter foo into the REPL to be
> evaluated, it would throw an unbound variable exception.

I wasn't aware of that CL behaviour.  IIUC that's actually conflating
two different things: creating an uninterned symbol and "unbinding"
an interned symbol.  I don't know of a way to unbind a variable through
Scheme, but you can set the symbol's value slot (0) to C_SCHEME_UNBOUND
in C.  This has to go with the warnings "Don't try this at home", and
"this voids your warranty". :)


Attachment: signature.asc
Description: Digital signature

reply via email to

[Prev in Thread] Current Thread [Next in Thread]