egison-3.7.13: sample/nishiwaki.egi

(define $nishiwaki-if
  (macro [$b $e1 $e2]
    (car (match-all b (matcher {[$ something {[#t {e1}] [#f {e2}]}]})
           [$x x]))))

(nishiwaki-if #t 1 2) ; 1

(nishiwaki-if #f 1 2) ; 2

(nishiwaki-if (eq? 1 1) 1 2) ; 1

(io (nishiwaki-if #t (print "OK") (print "NG"))) ; print "OK"

(io (nishiwaki-if #f (print "NG") (print "OK"))) ; print "OK"

(io (nishiwaki-if (eq? 1 1) (print "OK") (print "NG"))) ; print "OK"