Project Euler in JavaScript

euler1.js

var END_OF_WORLD = 'undefined';

function nextNumber(n) {
    return n + 1;
}

function numbers(base) {
    var n = base;
    return function() {
        return (n = nextNumber(n));
    };
}

function forEach(seq, fn) {
    var n = 0;
    while ((n = seq()) !== END_OF_WORLD) {
        if (fn(n) === false) {
            break;
        }
    }
}

function takeWhile(seq, pred) {
    return function() {
       var n = seq();
       return pred(n) ? n : END_OF_WORLD;
    };
}

function filter(seq, pred) {
    return function() {
        var n;
        while ((n = seq()) != END_OF_WORLD) {
            if (pred(n)) {
                return n;
            }
        }
        return END_OF_WORLD;
    };
}

function sum(seq) {
    var result = 0;
    forEach(seq, function(n) {
        result += n;
    });
    return result;
}

console.log(
    sum(
        filter(
            takeWhile(numbers(1), function(n) {
                return n < 1000;
            }),
            function(n) {
                return n % 3 == 0 || n % 5 == 0;
            }
        )
    )
);

euler2.js

var END_OF_WORLD = 'undefined';

function sequence(base, next) {
    var n = base;
    return function() {
        var result = n;
        n = next(n);
        return result;
    };
}

function fibonacci(p) {
    return [p[1], p[0] + p[1]];
}

function forEach(seq, fn) {
    var n = 0;
    while ((n = seq()) !== END_OF_WORLD) {
        if (fn(n) === false) {
            break;
        }
    }
}

function takeWhile(seq, pred) {
    return function() {
       var n = seq();
       return pred(n) ? n : END_OF_WORLD;
    };
}

function filter(seq, pred) {
    return function() {
        var n;
        while ((n = seq()) != END_OF_WORLD) {
            if (pred(n)) {
                return n;
            }
        }
        return END_OF_WORLD;
    };
}

function map(seq, fn) {
    return function() {
        return fn(seq());  
    };
}

function sum(seq) {
    var result = 0;
    forEach(seq, function(n) {
        result += n;
    });
    return result;
}

console.log(
    sum(
        filter(
            takeWhile(
                map(
                    sequence([1, 2], fibonacci),
                    function(p) {
                        return p[0];
                    }
                ),
                function(n) {
                       return n < 4000000;
                }
            ),
            function(n) {
                return n % 2 === 0;
            }
        )
    )
);