console.log([1, 2, 3].map(elem => elem - 1))？（part 2）

lambda-calculus-2.js

function array(lt) {
    let yes = f => y => f();
    let no = x => f => f(); 
    let when = c => c;

    let undef = (_ => _)();
    let is_undef = n => n === undef ? yes : no;

    let pair = l => r => f => f(l)(r);
    let left = p => p(l => _ => l);
    let right = p => p(_ => r => r);

    let nil = pair(undef)(undef);
    let con = h => t => pair(h)(t);
    let head = left;
    let tail = right;

    let isEmpty = l => is_undef(head(l));

    function arr(acc, l) {
        if(isEmpty(l) === yes) {
            return acc;
        } else {
            return arr(acc.concat([head(l)]), tail(l));
        }
    }
    return arr([], lt);
}

let lt = (f => (x => f(n => x(x)(n)))(x => f(n => x(x)(n))))(map => l => f => (l => (n => n === (_ => _)() ? (f => y => f()) : (x => f => f()))((p => p(l => _ => l))(l)))(l)(() => ((l => r => f => f(l)(r))((_ => _)())((_ => _)())))(() => (h => t => (l => r => f => f(l)(r))(h)(t))(f((p => p(l => _ => l))(l)))(map((p => p(_ => r => r))(l))(f))))((es => (l => ((f => (x => f(n => x(x)(n)))(x => f(n => x(x)(n))))(rev => r => l => (l => (n => n === (_ => _)() ? (f => y => f()) : (x => f => f()))((p => p(l => _ => l))(l)))(l)(() => r)(() => rev((h => t => (l => r => f => f(l)(r))(h)(t))((p => p(l => _ => l))(l))(r))((p => p(_ => r => r))(l)))))((l => r => f => f(l)(r))((_ => _)())((_ => _)()))(l))(es()))((f => (x => f(n => x(x)(n)))(x => f(n => x(x)(n))))(rcon => t => h => (n => n === (_ => _)() ? (f => y => f()) : (x => f => f()))(h)(() => t)(() => rcon((h => t => (l => r => f => f(l)(r))(h)(t))(h)(t))))((l => r => f => f(l)(r))((_ => _)())((_ => _)()))(1)(2)(3)))(elem => elem - 1);
console.log(array(lt));