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Re: Lexical vs. dynamic: small examples?


From: Emanuel Berg
Subject: Re: Lexical vs. dynamic: small examples?
Date: Sat, 14 Aug 2021 23:26:53 +0200
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/28.0.50 (gnu/linux)

tomas wrote:

> If you add nonlocal exits (exceptions, setjmp/longjmp,
> continuations), you are in hot water ;-)

Let's see, an exception is an exception...

setjmp/longjmp are C functions to save state and then
restore/resume execution at a specific location after
an error.
            
A continuation - the functional equivalent of the GOTO
statement <https://en.wikipedia.org/wiki/Continuation> - is
used in continuation-passing style computing, CPS, where an
explicit continuation function is sent to a function and
that gets called with the value instead of returning it.
So if f(a, f') = f'(f(a)) then f' is the continuation?

"Nonlocal exits unbind all variable bindings made by the
constructs being exited."
<https://www.gnu.org/software/emacs/manual/html_node/elisp/Nonlocal-Exits.html>

-- 
underground experts united
https://dataswamp.org/~incal




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