Add macros `thunk-let' and `thunk-let*'

* lisp/emacs-lisp/thunk.el (thunk-let, thunk-let*): New macros.
* test/lisp/emacs-lisp/thunk-tests.el:
(thunk-let-basic-test, thunk-let*-basic-test)
(thunk-let-bound-vars-cant-be-set-test)
(thunk-let-laziness-test, thunk-let*-laziness-test)
(thunk-let-bad-binding-test): New tests for `thunk-let' and
`thunk-let*.

* doc/lispref/eval.texi (Deferred Eval): New section.
* doc/lispref/elisp.texi: Update menu.

1 files changed, 4 insertions, 0 deletions

diff --git a/etc/NEWS b/etc/NEWS
index c47ca42d277..6b3e7fc244b 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -109,6 +109,10 @@ Snake and Pong are more playable on HiDPI displays.
 *** Completing filenames in the minibuffer via 'C-TAB' now uses the
 styles as configured by the variable 'completion-styles'.
 
+** New macros 'thunk-let' and 'thunk-let*'.
+These macros are analogue to 'let' and 'let*', but create bindings that
+are evaluated lazily.
+
 
 * New Modes and Packages in Emacs 27.1