FeM | Crockford functions

console.log('_________CHALLENGE 01________');

let add = (a,b)=>a+b;

let mul = (a,b)=>a*b;

let sub = (a,b)=>a-b;

console.log('sum:',add(3,4));

console.log('mul:',mul(3,4));

console.log('sub:',sub(3,4));

let identityf = a=>()=>a;// same as function(a){retunr function(){return a;};}

let three = identityf(3);

console.log('three exec:',three());

let addf = a=>{

return function(b){

return a+b;

};

};

console.log('addf:',addf(3)(4));

let liftf = function(binaryFunc){

return function(a){

return function(b){

return binaryFunc(a,b);

};

};

};

let add2 = liftf(add);

console.log('liftf:',add2(3)(4));

/////////////////////////////////////////challenge 2///////////////////////////////

console.log('_________CHALLENGE 02________');

//let curry = function(binaryFunc, a){

// return function(b){

// return binaryFunc(a,b)

// }

//}

let curry = (bFunc, a)=> liftf(bFunc)(a);

let add3 = curry(add,3);

console.log('add3:',add3(5));

//let inc = addf(1);

//let inc = liftf(add)(1);

let inc = curry(add,1);

console.log('inc:',inc(inc(5)));

////////////////////challenge 3////////////////////////////

console.log('_________CHALLENGE 03________');

let twice = bf=>(a)=>bf(a,a);

let doubl = twice(add);

let square = twice(mul);

console.log('twice:',doubl(3));

console.log('twice2:',square(3));

let reverse = bf=>(a,b)=>bf(b,a);

let bus = reverse(sub);

console.log('reverse:',bus(2,3));

let composeu = (ufa, ufb)=>a=>ufb(ufa(a));

console.log('compose U:',composeu(doubl, square)(5));

let composeb = (bfa,bfb)=>(a,b,c)=>bfb(bfa(a,b),c);

console.log('compose B:', composeb(add, mul)(2,3,7));

let limit = (func, count)=>{

return function (a,b){

if (count){

count-=1;

return func(a,b);

}else{

return undefined;

}

};

};

let limitedAdd = limit(add,1);

console.log('limitedAdd 1:',limitedAdd(2,3));

console.log('limitedAdd 2:',limitedAdd(3,4));

console.log('limitedAdd 3:',limitedAdd(3,4));

////////////////////////challenge 04///////////////////////////////

console.log('_________CHALLENGE 04________');

let from = arg=>{

return ()=>{

let buffer = arg;

arg+=1;

return buffer;

};

};

let index = from(0);

console.log('call 01 of index:',index());

console.log('call 02 of index:',index());

console.log('call 03 of index:',index());

let to = (generator, limit)=>{

return ()=>{

let x = generator();

if (x<limit){

return x;

}

return undefined;

};

};

let limitedIndex = to(from(1), 3);

console.log('call 01 of limited index:', limitedIndex());

console.log('call 02 of limited index:', limitedIndex());

console.log('call 03 of limited index:', limitedIndex());

let fromTo = (a, b)=>{

return to(from(a), b);

};

let fromToIndex = fromTo(0, 3);

console.log('call 01 of fromTo index:', fromToIndex());

console.log('call 02 of fromTo index:', fromToIndex());

console.log('call 03 of fromTo index:', fromToIndex());

console.log('call 04 of fromTo index:', fromToIndex());

let element = (arr, gen)=>{

return ()=>{

let index = gen();

if(index!==undefined){

return arr[index];

}

return undefined;

};

};

let ele = element(['a','b','c','d'],fromTo(1, 3));

console.log('call 01 of element:', ele());

console.log('call 02 of element:', ele());

console.log('call 03 of element:', ele());

let elementV2 = (arr, gen)=>{

if (gen ===undefined){

gen = fromTo(0,arr.length);

}

return element(arr, gen);

};

let eleV2 = elementV2(['a','b','c','d']);

console.log('call 01 of elementV2:', eleV2());

console.log('call 02 of elementV2:', eleV2());

console.log('call 03 of elementV2:', eleV2());

console.log('call 04 of elementV2:', eleV2());

console.log('call 05 of elementV2:', eleV2());

////////////////////////challenge 05///////////////////////////////

console.log('_________CHALLENGE 05________');

let collect = (gen,arr)=>{

return ()=>{

let buffer = gen();

if (buffer!== undefined){

arr.push(buffer);

}

return buffer;

}

};

let array =[];

let col = collect(fromTo(0,2),array);

console.log('call 01 of collector:', col());

console.log('call 02 of collector:', col());

console.log('call 03 of collector:', col());

console.log('call 04 of collector:', col());

console.log('array:', array);

//Write a filter function that takes a generator and a predicate and produces a generator that produces only the values approved by the predicate.

let filter = (gen, pred)=>{

return ()=>{

let value = gen();

while(!pred(value) && value!==undefined){

value = gen();

}

return value;

};

};

let fil = filter (fromTo(0,5), value=>{return value%3===0;});

console.log('call 01 of filter:', fil());

console.log('call 02 of filter:', fil());

console.log('call 03 of filter:', fil());

console.log('call 04 of filter:', fil());

//Write a concat function that takes two generators and produces a generator that combines the sequences

let concat = (gen1, gen2)=>{

return ()=>{

let buffer = gen1();

if (buffer !== undefined){

return buffer

}

return gen2();

}

};

let con = concat (fromTo(0,3), fromTo(0,2));

console.log('call 01 of concat:', con());

console.log('call 02 of concat:', con());

console.log('call 03 of concat:', con());

console.log('call 04 of concat:', con());

console.log('call 05 of concat:', con());

console.log('call 06 of concat:', con());

////////////////////////challenge 06///////////////////////////////

console.log('_____________CHALLENGE 06_____________');

//Make a function gensymf that makes a function that generates unique symbols

let gensymf = symbol=>{

let count = 0;

return ()=>{

count += 1;

return symbol.toString()+count

};

};

let geng = gensymf('G');

let genh = gensymf('H');

console.log('call 01 of geng:', geng());

console.log('call 01 of genh:', genh());

console.log('call 02 of geng:', geng());

console.log('call 02 of genh:', genh());

//Make a function fibonaccif that returns a generator that will return the next fibonacci number

let fibonaccif = (a, b)=>{

return ()=>{

let next = a;

a = b;

b+= next;

return next;

}

}

let fib = fibonaccif(0,1);

console.log('call 01 of fib:', fib());

console.log('call 02 of fib:', fib());

console.log('call 03 of fib:', fib());

console.log('call 04 of fib:', fib());

console.log('call 05 of fib:', fib());

console.log('call 06 of fib:', fib());