They are basically the same macros, but without the use of bindings (more brevity).

So if-let and when-let are not really anaphoric.

In Common Lisp, I use b-when and b-if that Kenny Tilton wrote:

  (defmacro b-when (bindvar boundform &body body)
    `(let ((,bindvar ,boundform))
       (when ,bindvar
         ,@body)))

  (defmacro b-if (bindvar boundform yup &optional nope)
    `(let ((,bindvar ,boundform))
       (if ,bindvar
           ,yup
         ,nope)))

Usage:

  (b-when foo (plusp 1)
	(frob foo))