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Re: Meaning of <=> in the context of procedures


From: Linus Björnstam
Subject: Re: Meaning of <=> in the context of procedures
Date: Wed, 02 Jun 2021 18:21:39 +0200
User-agent: Cyrus-JMAP/3.5.0-alpha0-519-g27a961944e-fm-20210531.001-g27a96194

To reply to myself: it is an exported identifier that is used in a 
define-json-mapping. It is good form for macros to export all its auxiliary 
syntax. 


-- 
  Linus Björnstam

On Wed, 2 Jun 2021, at 18:12, Linus Björnstam wrote:
> It is a trick to allow using the symbol '<=> as an identifier instead 
> of quoting it. Nothing special. Guile-json probably uses it somehow.
> 
> If it is used as auxiliary syntax in a macro, it is probably exported 
> so guile can warn that it is being shadowed instead of (or rather: in 
> addition to) producing bad error messages.
> 
> -- 
>   Linus Björnstam
> 
> On Wed, 2 Jun 2021, at 16:06, Mortimer Cladwell wrote:
> > Hi,
> > What does <=> mean/do?
> > It can be found in guile-json in the (json record) module, line 33:
> > 
> > 33 #:export (<=> define-json-mapping define-json-type))
> > 
> > Not mentioned in the entire Guile manual. Happens to be defined on line 36
> > of the module:
> > 
> > 36  (define <=> '<=>)
> > 
> > I didn't find that very helpful :)
> > Thanks
> > Mortimer
> > 
> 
> 



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