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The name of 'maybe could be... um... "combinetrue".
(let x init (when (f x) ...body...)) ==> (checklet x f init ...body...)
(def fn-checklet (test x body) (test&body x)) (mac checklet (var test x . body) `(fn-checklet ,test ,x (fn (,var) ,@body)))
Whoops, "construe" is an English word. XD Better call it "cons-true".