Subject: Re: bug#60225: [PATCH] records: match-record supports specifying a different variable name.

From: Ludovic Courtès <[email-masked]>
Date: Tue, 27 Dec 2022 23:53:11 +0100

Attila Lendvai <[email-masked]> skribis:

> * tests/records.scm ("match-record, syntactic interference"): New failing test.
> ---
>
> i'm not sure what's going on here, but it looks like a bug to me.

[...]

> +           (let (,@bindings)            ; but here it does interfere
> +             (match-record (foo (second 2)) <foo>
> +               (first second)
> +               (list first second))))))

This has to do with how macro “literals” are matched (info "(guile)
Syntax Rules"):

     A literal matches an input expression if the input expression is an
  identifier with the same name as the literal, and both are unbound(1).

     Although literals can be unbound, usually they are bound to allow
  them to be imported, exported, and renamed.  *Note Modules::, for more
  information on imports and exports.  In Guile there are a few standard
  auxiliary syntax definitions, as specified by R6RS and R7RS:

In the example above, the ‘let’ binding for ‘second’ was shadowing the
other ‘second’.

(I think this was recently discussed on guix-devel or something.)

Ludo’.