anchor.diff:                (cond
                   [,(caar vars) (when-let* ,(cdr vars) ,@body)]
                   [true nil]))
  -            ,(cadar vars))]))
  +            ,(make-binding (cdar vars)))]))
   
   (defmacro when-with (var &body)
     "Bind the PAIR var of the form `(name value)`, only evaluating BODY if the
  
positive.code:      foo
     ```"
    (if (! (nil? vars))
      `((lambda (,(caar vars)) (let* ,(cdr vars) ,@body)) ,(cadar vars))
      `((lambda () ,@body))))
  
  ;; Binds a variable to an expression
  
negative.code:    ```
     does."
    `((lambda ,(cars vars)
       (when (and ,@(cars vars)) ,@body))
      ,@(map make-let-binding vars)))
  
  (defmacro when-let* (vars &body)
    "Bind each pair of `(name value)` of VARS, checking if the value is truthy
  