Thanks for the work!
I didn’t find anything to be picky about yet in the implementation.

Now there are two things could go further.
1. About the port closing, I don’t insist on my previous suggestion right
now. There may be arguments against it by folks. I’m fine with any.

2. To complete a promising patch, it’s better to have test cases. You may
take a look at the existing tests to learn how.

Best regards.

On Reiwa 6 Dec 17, Tue at 0:22 Adam Faiz <adam.faiz@disroot.org> wrote:

> From 302159fe61d9df526911ead8ea6ad823ad8b0443 Mon Sep 17 00:00:00 2001
> From: AwesomeAdam54321 <adam.faiz@disroot.org>
> Date: Sun, 15 Dec 2024 23:48:30 +0800
> Subject: [PATCH 1/2] rdelim: Add new procedure `for-rdelim-in-port`.
>
> * module/ice-9/rdelim.scm (for-rdelim-in-port): Add it.
> (for-delimited-in-port): Define as a specialised `for-rdelim-in-port`.
> (for-line-in-file): Define as a specialised `for-delimited-in-port`.
>
> These procedures provide a backbone for parsing, with domain-specific
> logic implemented as a separate procedure to be passed as an argument.
> ---
>  module/ice-9/rdelim.scm | 35 ++++++++++++++++++++++++++++++++++-
>  1 file changed, 34 insertions(+), 1 deletion(-)
>
> diff --git a/module/ice-9/rdelim.scm b/module/ice-9/rdelim.scm
> index d2cd081d7..0bbaaf904 100644
> --- a/module/ice-9/rdelim.scm
> +++ b/module/ice-9/rdelim.scm
> @@ -23,7 +23,10 @@
>  ;;; similar to (scsh rdelim) but somewhat incompatible.
>
>  (define-module (ice-9 rdelim)
> -  #:export (read-line
> +  #:export (for-delimited-in-port
> +            for-line-in-file
> +            for-rdelim-in-port
> +            read-line
>              read-line!
>              read-delimited
>              read-delimited!
> @@ -206,3 +209,33 @@ characters to read.  By default, there is no limit."
>               line)
>        (else
>         (error "unexpected handle-delim value: " handle-delim)))))
> +
> +(define* (for-rdelim-in-port port proc rdelim-proc
> +                             #:key (stop-pred eof-object?))
> +  "Call PROC for every (RDELIM-PROC PORT) in PORT until STOP-PRED returns
> #t.
> +RDELIM-PROC has to advance through PORT with every call."
> +  (let loop ((rdelim (rdelim-proc port)))
> +    (cond ((stop-pred rdelim)
> +           (close-port port))
> +          (else
> +           (proc rdelim)
> +           (loop (rdelim-proc port))))))
> +
> +(define* (for-delimited-in-port port proc
> +                               #:key (delims "\n") (handle-delim 'trim))
> +  "Call PROC for every delimited line in PORT until the eof-object is
> reached."
> +  (for-rdelim-in-port port proc
> +                     (lambda (port)
> +                       (read-delimited delims port handle-delim))))
> +
> +(define* (for-line-in-file file proc
> +                           #:key (encoding #f) (guess-encoding #f))
> +  "Call PROC for every line in FILE until the eof-object is reached.
> +FILE must be a filename string.
> +
> +The line provided to PROC is guaranteed to be a string."
> +  (call-with-input-file
> +      file
> +    (lambda (port)
> +      (for-delimited-in-port port proc))
> +    #:encoding encoding #:guess-encoding guess-encoding))
> --
> 2.41.0
>