Then perhaps you can define 'defho in terms of 'mac and 'w/hof, maybe? The Arc solution: throw more macros at it.

Regarding (x . [f it]) :

In canonical arc2, [f it] is (fn (_) (f it)), so (x . [f it]) becomes (x fn (_) (f it)) . In Anarki, [f it] is (make-br-fn (f it)), so (x . [f it]) becomes (x make-br-fn (f it))

This makes the use of [] problematical.

'w/hof is trivially implementable, 'defho much less so due to the syntax.

w/hof is also more general, at the expense of being more talkative.

In fact it might be better to do things this way:

  (mac while (cond . body)
    (w/hof (cond (fn () ,cond)
            body (fn () ,@body))
      ((afn ()
         (when (cond)
           (body)
           (self))))))

  (mac aif (cond then (o else))
    (w/hof (cond ,cond
            then (fn (it) ,then)
            else (fn () ,else))
      (if cond
          (then cond)
          (else))))