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On 12/16/2023, cor@clsnet.nl wrote:

> Any marginally usable programming language approaches an ill
>        defined barely usable re-implementation of half of common-lisp

Paul Graham:

I consider Loop one of the worst flaws in CL, and an example
to be borne in mind by both macro writers and language designers.


[In "ANSI Common Lisp", Graham makes the following comments:]

> The loop macro was originally designed to help inexperienced
> Lisp users write iterative code. Instead of writing Lisp code,
> you express your program in a form meant to resemble English,
> and this is then translated into Lisp.  Unfortunately, loop is
> more like English than its designers ever intended: you can
> use it in simple cases without quite understanding how it
> works, but to understand it in the abstract is almost
> impossible.
>   ....
> the ANSI standard does not really give a formal specification
> of its behavior.
>   ....
> The first thing one notices about the loop macro is that it
> has syntax.  A loop expression contains not subexpressions but
> clauses.  The clauses are not delimited by parentheses;
> instead, each kind has a distinct syntax.  In that, loop
> resembles traditional Algol-like languages.  But the other
> distinctive feature of loop, which makes it as unlike Algol as
> Lisp, is that the order in which things happen is only
> loosely related to the order in which the clauses occur.
>   ....
> For such reasons, the use of loop cannot be recommended.

He wrote:

"the ANSI standard does not really give a formal specification
of its behavior."

In other words, Loop is "ill-defined".