null created by anonymous - https://repl.it/EJs8/9

EJs8-9.js

var _ = "Placeholder_secret_constant";
var placeholder_support = f => 
	(...outer_args)=>{
		if(outer_args.filter(x=>x==_).length === 0) {
			if(outer_args.length<f.length){
				while(outer_args.length<f.length)outer_args.push(_);
				return placeholder_support(f)(...outer_args);
			} else {
				return f(...outer_args);
			}
		}
		else {
			var args = outer_args.map((x,i)=>[x,i]);
			return (...inner_args)=>{
				inner_args.map((x,i)=>[x,args.filter(y=>y[0]==_)
						  					 .map(y=>y[1])[i]])
						  .forEach(x=>{
						  	if(typeof(x[1])!=="undefined")
						  		args[x[1]][0]=x[0];
						  	else
						  		args.push([x[0],args.length]);
						  });
				return (placeholder_support(f))(...args.map(x=>x[0]));
			};
		}
	};
// var f = (a,b,c,d,e)=>a+b+c+d+e;
// var f = (a,b,c,d,e)=>console.log(a,b,c,d,e);
var f = (a,b,c,...args)=>console.log(a,b,c,...args);
f=placeholder_support(f);

f(1,_,2,4,_)(3,_)(3);
f(1,_,_,_,_)(2)(3)(4)(5);
// f(1)(2)(3)(4)(5);
f(1)(2)(3,_)(4);
f(1)(2)(3,_)(4,_)(5,6);
f(1,_,_,_,2)(3,_,4)(5);

var g = (...args)=>console.log(...args);
g=placeholder_support(g);

g(_,_,2)(1)(3);
g(_)(1,2,3,4,5);