From cf4dba3899eef0a88bf4032bec5cf45c56a77077 Mon Sep 17 00:00:00 2001
From: Daanturo <daanturo@gmail.com>
Date: Thu, 17 Nov 2022 13:57:20 +0700
Subject: [PATCH] Define macro dlet*

* lisp/subr.el: implementation.
* doc/lispref/variables.texi: documentation.
* etc/NEWS: announce it, also add dlet's non-backward compatible
breakage.
---
 doc/lispref/variables.texi |  8 ++++++++
 etc/NEWS                   | 10 ++++++++++
 lisp/subr.el               |  8 ++++++++
 3 files changed, 26 insertions(+)

diff --git a/doc/lispref/variables.texi b/doc/lispref/variables.texi
index 7206f2acd2..c574ffaf09 100644
--- a/doc/lispref/variables.texi
+++ b/doc/lispref/variables.texi
@@ -303,6 +303,14 @@ Binding}), but it's impractical to @code{defvar} these variables.
 the forms, and then make the variables non-special again.
 @end defspec
 
+@defspec dlet* (bindings@dots{}) forms@dots{}
+This form is like @code{dlet}, but each valueform can refer to the
+symbols already bound previously, like what @code{let*} is to
+@code{let} (actually this is Emacs 28's old @code{dlet}, as from Emacs
+29 it no longer let bindings refer to the preceding symbols in this
+same form).
+@end defspec
+
 @defspec named-let name bindings &rest body
 This special form is a looping construct inspired from the
 Scheme language.  It is similar to @code{let}: It binds the variables in
diff --git a/etc/NEWS b/etc/NEWS
index 0b8f4539f9..1e9b1ce279 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -2913,6 +2913,10 @@ when visiting JSON files.
 
 * Incompatible Lisp Changes in Emacs 29.1
 
++++
+** dlet now uses let internally instead of let*.
+---
+
 +++
 ** 'format-prompt' now uses 'substitute-command-keys'.
 This means that both the prompt and 'minibuffer-default-prompt-format'
@@ -3269,6 +3273,12 @@ The following generalized variables have been made obsolete:
 
 * Lisp Changes in Emacs 29.1
 
+
++++
+** New macro 'dlet*'.
+Like what 'let*' is to 'let', functionally identical to the old 'dlet'
+in Emacs 28.
+
 +++
 ** Interpreted closures are "safe for space".
 As was already the case for byte-compiled closures, instead of capturing
diff --git a/lisp/subr.el b/lisp/subr.el
index 6b83196d05..ddc48b554e 100644
--- a/lisp/subr.el
+++ b/lisp/subr.el
@@ -2155,6 +2155,14 @@ all symbols are bound before any of the VALUEFORMs are evalled."
                binders)
      (let ,binders ,@body)))
 
+(defmacro dlet* (binders &rest body)
+  "Like `let*' but using dynamic scoping."
+  (declare (indent 1) (debug let))
+  `(let (_)
+     ,@(mapcar (lambda (binder)
+                 `(defvar ,(if (consp binder) (car binder) binder)))
+               binders)
+     (let ,binders ,@body)))
 
 (defmacro with-wrapper-hook (hook args &rest body)
   "Run BODY, using wrapper functions from HOOK with additional ARGS.
-- 
2.38.1