| I took a very small amount of time to translate On Lisp's scheme implementation of choose and fail into Arc. It is quite elegant, I must say. Here it is: (= paths* ()
failsym* '@)
(def choose (choices)
(if (no choices)
(fail)
(ccc (fn (cc)
(push (fn ()
(cc (choose (cdr choices))))
paths*)
(car choices)))))
(= fail nil)
(ccc (fn (cc)
(= fail
(fn ()
(if (no paths*)
(cc failsym*)
((pop paths*)))))))
One problem: instead of returning the failsym when all possibilities fail, it gives this error: Error: "read-char: input port is closed"
Not sure what that's all about. |
