Fwd: expression and definition context in Scheme

[Damien Mattei]

---------- Forwarded message ---------
From: Damien Mattei <damien.mattei@gmail.com>
Date: Mon, Aug 29, 2022 at 12:09 PM
Subject: Re: _expression_ and definition context in Scheme
To: Maxime Devos <maximedevos@telenet.be>

yes , the same with 'while too, i will make it in my Scheme+ to allow inner 'define in those blocks without other stuff (in Scheme+ i had already a simple macro : (& ev ...) = (let () ev ...) that replace 'begin when 'define is needed in blocks.

regards,

Damien

On Sun, Aug 28, 2022 at 11:30 AM Maxime Devos <maximedevos@telenet.be> wrote:

On 28-08-2022 08:40, Damien Mattei wrote:

in fact my thought was not clear, perhaps just  allow a 'define in an instructions as 'when in my example , 'define-ed variable would then be local one in the block of 'when, will it change something in scheme implementation in a bad way?

Are you asking for 'when' to implicitly wrap its body in a (let () ...)?

If so, that's trivial to implement, without changing the Scheme implementation:

(define-syntax-rule (when cond exp ...)
  (if cond
      (let () exp ...)))

Greetings,
Maxime.