Why don't when-let and if-let support multiple bindings by default?

Question

Why don\'t when-let and if-let support multiple bindings by default?

So:

(when-let [a ...
           b ...]
  (+ a b))
         


        

Answer 1

If you use cats, then there is a mlet function that you might find useful :

(use 'cats.builtin)
(require '[cats.core :as m])
(require '[cats.monad.maybe :as maybe])

(m/mlet [x (maybe/just 42)
         y nil]
  (m/return (+ x y)))
;; => nil

As you can see, the mlet short-circuits when encountering a nil value.

(from section 6.5.1 nil)