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From: Aidan Kehoe <kehoea@parhasard.net>
Newsgroups: comp.lang.lisp,comp.lang.scheme
Subject: Re: REPL in Lisp
Date: Sun, 14 Jul 2024 22:03:53 +0100
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 Ar an ceathrú lá déag de mí Iúil, scríobh George Neuner: 

 > On Sat, 13 Jul 2024 08:24:27 +0100, Aidan Kehoe <kehoea@parhasard.net>
 > wrote:
 > 
 > >
 > > Ar an dara lá déag de mí Iúil, scríobh Kaz Kylheku: 
 > >
 > > > On 2024-07-11, Lawrence D'Oliveiro <ldo@nz.invalid> wrote:
 > > > > On Wed, 10 Jul 2024 19:11:17 -0700, HenHanna wrote:
 > > > >
 > > > >> the acronym (?)  REPL  must be new in Lisp   (and Scheme)
 > > > >> 
 > > > >> i'm sure i  never saw it (used or mentioned)   25  years ago.
 > > > >
 > > > > There are many new terms coined for old concepts. Like “capture” for 
 > > > > “lexical binding”, or “dependency injection” for “callback”.
 > > > 
 > > > Lexical binding does not imply closure/capture. 
 > >
 > >I’ve never seen “capture” used as a general term for closures or for lexical
 > >scope in this way; are we sure it’s what was meant?
 > 
 > "Capture" is exactly what was meant.  
 > 
 > When a closure references variables from external scopes - that is
 > things are that are neither arguments nor locals - it is said to
 > "capture" those variables.

Or to “close around” those variables.

Your reference to C++ clarified things, I had and have no interest in using
that language and so I had not known that “capture” is used for the Lisp
“closure” in recent versions of C++ that support it.

 > Lisp and Scheme create a copy of the captured variable in the closure
 > and compile the code to reference the closure's copy rather than the
 > original [which may no longer exist or may not be in scope when the
 > closure code finally is executed].
 > 
 > > > C has lexical scoping without capture: the bindings are destroyed
 > > > when their associated scope terminates.
 > 
 > And C++ now has closures with control over capture.  If you choose not
 > to capture, external variables that are referenced must be in scope
 > (at their right locations) if and when the closure code is executed.
 > 

-- 
‘As I sat looking up at the Guinness ad, I could never figure out /
How your man stayed up on the surfboard after fourteen pints of stout’
(C. Moore)