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RE: Double unquote/unquote-splicing
From: |
Drew Adams |
Subject: |
RE: Double unquote/unquote-splicing |
Date: |
Mon, 4 Nov 2013 11:01:19 -0800 (PST) |
> > "The backquote syntax was particularly powerful when nested. This
> > occurred primarily within macro-defining macros; because such were
> > coded primarily by wizards, the ability to write and interpret nested
> > backquote expressions was soon surrounded by a certain mystique.
> > Alan Bawden of MIT acquired a particular reputation as backquote-
> > meister in the early days of the Lisp Machine." - "The Evolution of
> > Lisp", Gabriel, Steele.
>
> That sounds about right: it's only for wizards.
No, that is exactly backwards. Please note: "The backquote syntax was
__particularly powerful when nested__." That's about power simplifying
understanding by humans.
Read the article for explanation and good examples. The point of that
passage is that _without_ backquote syntax the kinds of things you can
do using nested backquotes are *really* complicated without them. The
point is that backquote syntax is _especially_ good at simplifying in
the case of nested backquotes.
What is for wizards is the need to write code of this kind: the kinds
of things that nested backquotes simplify. Those use cases are not so
common, but if you have such a use case then you _really_ want to have
nested backquote syntax. That's the point of the quoted passage.
The full article is here:
http://extravagaria.com/Files/HOPL2-Uncut.pdf
> Nested backquotes were largely broken in Elisp and it took many
> years for someone to notice. I do use them occasionally, but only in
> fairly simple ways. The resulting code is largely impenetrable, so
> I don't want to encourage it.
Nested backquote syntax should be neither encouraged nor discouraged.
The point is that compared to the alternative it is a lot simpler.
- Double unquote/unquote-splicing, Nathan Trapuzzano, 2013/11/04
- Re: Double unquote/unquote-splicing, Stefan Monnier, 2013/11/04
- Re: Double unquote/unquote-splicing, Nathan Trapuzzano, 2013/11/04
- Re: Double unquote/unquote-splicing, Nathan Trapuzzano, 2013/11/04
- Re: Double unquote/unquote-splicing, Stefan Monnier, 2013/11/04
- RE: Double unquote/unquote-splicing,
Drew Adams <=
- Re: Double unquote/unquote-splicing, Nathan Trapuzzano, 2013/11/04
- Re: Double unquote/unquote-splicing, Stefan Monnier, 2013/11/04
- Re: Double unquote/unquote-splicing, Nathan Trapuzzano, 2013/11/05
- Re: Double unquote/unquote-splicing, Stefan Monnier, 2013/11/05
- Re: Double unquote/unquote-splicing, Stephen J. Turnbull, 2013/11/04
- Re: Double unquote/unquote-splicing, Nathan Trapuzzano, 2013/11/05
- Re: Double unquote/unquote-splicing, Stephen J. Turnbull, 2013/11/05