prog funcional em js. wip

funcional.js

<script type="text/javascript">

console.log("ola mundo");

function par(a, b) {
	return function(f) {
		return f(a, b);
	}
}

function head(l) {
	return l(function(a, b) {return a;});
}

function tail(l) {
	return l(function(a, b) {return b;});
}


console.log(head(par(1,2)));
console.log(tail(par(1,2)));

function foreach(l, f) {
	f(head(l));
	if(tail(l) == null) return;
	foreach(tail(l), f);
}

foreach(par(0, par(1, par(2, null))), function(x) {console.log(x);});

function lista(a) {
	if(a.length == 0) return null;
	return par(a[0], lista(a.slice(1)));
}

var x = lista([0,1,2,3,4,5]);
foreach(x, function(x) {console.log(x);});

function converte(l) {
	if(tail(l) == null) return [head(l)];
	return [head(l)].concat(converte(tail(l)));
}

function map(l, f) {
	if(l == null) return null;
	return par(f(head(l)), map(tail(l), f));
}

var y = map(x, function(x) {return x*2;});
console.log(converte(y));


function filter(l, f) {
	if(l == null) return null;
	return f(head(l)) ? par(head(l), filter(tail(l), f)) :
				filter(tail(l), f);
}

var z = filter(y, function(x) {return x%4==0;});
console.log(converte(z));

function fold(l, i, op) {
	if(l == null) return i;
	return op(head(l), fold(tail(l), i, op));
}

function foldl(l, i, op) {
	if(l == null) return i;
	return foldl(tail(l), op(i, head(l)), op);
}

var zz = foldl(x, 0, function(a,b) {console.log(a,b); return a+b;});
console.log(zz);

function map2(l, f) {
	return fold(l, null, 
		function(a, b) { 
			return par(f(a), b);}
		);
}


function count(l, f) {
	return fold(l, 0,
		function(a, b) {
			return f(a) ? b+1 : b;
		});
}


var yy = map2(x, function(x) {return x*2;});
console.log(converte(yy));
console.log(count(yy, function(x) {return x%4==0;}));



</script>