如何在PicoLisp中返回带有“cond”的默认值

当

cond

语句不满足其他条件时，我试图返回一个默认值。如何在PicoLisp中实现这一点

(de fib (n)
  (cond
    ((= n 0) 0)
    ((= n 1) 1)
    (+ (fib (- n 1)) (fib (- n 2))) ) )

(prinl (fib 1)) # prints 1
(prinl (fib 5)) # prints nothing
(bye)

必须使用全局函数返回默认值

(let (Foo "bar")
  (cond
    ((not Foo) "No foo for you")
    ((lst? Foo) (map 'my-list-function Foo))
    ((= Foo "bar") "Foobar")
    "Nothing is true" ) )

(de fib (n)
  (cond
    ((= n 0) 0)
    ((= n 1) 1)
    (T (+ (fib (- n 1)) (fib (- n 2)))) ) )

(prinl (fib 1)) # prints 1
(prinl (fib 5)) # prints 5
(bye)