Re: [stack] QuoteAndEval

On 14/5/08 6:35 AM, "John Cowan" <[email protected]> wrote:
> 
> Manfred Von Thun scripsit:
> 
>> > The beauty of the various Unix utilities is that you can pipe the output
>> > of one to become the input to the next. The backquote substitution
>> > can make good use of it.
> 
> Backquotes -- as is clearly shown by the alternative syntax $(...) --
> essentially belong to the lexical level of the shell, just like $name
> substitution. 
> 
Thank you, I did not know about the alternative syntax. My relevant manual
(in this case Bourne¹s ..The Unix Programming Environment.. 1982 (?)
does not have it. But my eMac here knows about it...

>  So they are very like Lisp macros: code inside backquotes
> runs in a subshell to produce *source code* which is then evaluated by
> the main shell in context, just as a Lisp macro runs in an subordinate
> evaluator to generate Lisp code to be run by the main evaluator in
> context.

Yes, Lisp¹s macros .. I have never used them in the 5 or 6 pages of Lisp
that I have written. Oleg has some amazing things to say about
various lambda calculus interpreters hidden inside Lisp and Scheme,
with call by name and call by value. I can¹t find it right now, sorry.

  - Manfred



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