imperative2declarative.js

//TRY 1
// const nextCharForNumberString = function(str){
//     const trimmed = str.trim();
//     const number = parseInt(trimmed);
//     const nextNumber = number + 1;
//     return String.fromCharCode(nextNumber);
// }

//TRY 2
// const nextCharForNumberString = function(str){
//     return String.fromCharCode((parseInt(str.trim()) + 1));
// }

//TRY 3
const Box = function(x){
    return {
        map: function(f){
            return Box(f(x))
            },
        inspect: function(){
            return `Box(${x})`;
        },
        fold: function(f){
            return f(x);
        }
    }
}

const nextCharForNumberString = function(str){
    return Box(str)
    .map(s => s.trim())
    .map(s => parseInt(s))
    .map(i => i + 1)
    .map(i => String.fromCharCode(i))
    .fold(c => c);
}

const result = nextCharForNumberString(' 64 ');
console.log(result)