bloglang/13/examples/list.txt

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data List a = { Nil, Cons a (List a) }
defn map f l = {
case l of {
Nil -> { Nil }
Cons x xs -> { Cons (f x) (map f xs) }
}
}
defn foldl f b l = {
case l of {
Nil -> { b }
Cons x xs -> { foldl f (f b x) xs }
}
}
defn foldr f b l = {
case l of {
Nil -> { b }
Cons x xs -> { f x (foldr f b xs) }
}
}
defn list = { Cons 1 (Cons 2 (Cons 3 (Cons 4 Nil))) }
defn add x y = { x + y }
defn sum l = { foldr add 0 l }
defn skipAdd x y = { y + 1 }
defn length l = { foldr skipAdd 0 l }
defn main = { sum list + length list }