Re: Elisp threading macros

["Alfred M. Szmidt" <ams@gnu.org>]

   `-some->' is useful in cases like this:

   (let (foo (function-which-may-return-nil))
     (when foo
       (bar foo)))

   which can be rewritten, much cleaner, as

   (-some-> foo function-which-may-return-nil bar)

Those two forms aren't the same.  This is the macroexpand-all version:

(let ((result (let ((result foo))
		(if result
		    (progn (function-which-may-return-nil result))))))
  (if result
      (progn (bar result))))

Notice how e.g., function-which-may-return-nil actually gets the foo
argument.  And the semantics are also different.

While the above might seam cleaner, since it is shorter, it is much
harder to modify, maintain and reason about.