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Resolved: ! often means may, not will [WAS: Re: take! 0==1?]
From: |
Jan Nieuwenhuizen |
Subject: |
Resolved: ! often means may, not will [WAS: Re: take! 0==1?] |
Date: |
Fri, 12 Jul 2013 18:57:36 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.2 (gnu/linux) |
William ML Leslie writes:
> Actually, I should clarify a few things, but this discussion probably
> belongs on guile-user.
I realise that now, reading below...
> Whenever the documentation says 'may', it really means it. You
> absolutely cannot rely on the side-effecting behaviour, because an
> implementation that does no mutation whatsoever is a valid
> implementation of (take!), according to the documentation. All you're
> saying by using (take!) is, if it is more efficient to do so by
> altering the list, then please do.
Thank you for this clue-bat.
Wow, I never realised that !/_x is only a performance/ugliness thingy,
except when used with set!. I somehow assumed `!' meant: will alter
in-place. My bad.
Is there really a good reason for exposing such performance
considerations to the user; can't the compiler [often] tell whether it's
safe to modify in place?
Greetings, Jan
--
Jan Nieuwenhuizen <address@hidden> | GNU LilyPond http://lilypond.org
Freelance IT http://JoyofSource.com | AvatarĀ® http://AvatarAcademy.nl
- take! 0==1?, Jan Nieuwenhuizen, 2013/07/12
- Re: take! 0==1?, William ML Leslie, 2013/07/12
- Re: take! 0==1?, William ML Leslie, 2013/07/12
- Resolved: ! often means may, not will [WAS: Re: take! 0==1?],
Jan Nieuwenhuizen <=