main.mo

import List "mo:base/List";

actor Example {
    var sum = 0;
    private var test = List.fromArray<Nat>([5,4,3,2,1,0]);
    private var test1 = List.nil<Nat>();
    
    let f2 = func self(x: Nat) {
        sum := sum + x;
    };

    public func sumf() : async Nat {
        List.iterate(test, f2);
        return sum;
    };

    public func set() : async [Nat] {
        List.iterate(test, func(x: Nat){
            test1 := List.push<Nat>(x, test1); // 注意 List 里面 push 的实现是在 List 头加入的，因此反序
        });
        return List.toArray(test1);
    };
};

/* 结果
➜  beta dfx canister call beta sumf
(15)
➜  beta sudo dfx canister  install beta -m=reinstall
➜  beta dfx canister call beta set
(vec { 0; 1; 2; 3; 4; 5 })
➜  beta
*/