javascript - Is tail recursion merely a special case of CPS? -

-

i've implemented map in tail recursive , continuation passing style. both versions quite similar:

var inc = x => ++x; var xs = [1,2,3,4,5];  var mapr = f => xs => {     var rec = acc => {         acc[acc.length] = f(xs[acc.length]);         return acc.length < xs.length ? rec(acc) : acc;     }      return rec([]); }  mapr(inc)(xs); // [2,3,4,5,6]  var mapc = f => xs => cc => {     var rec = acc => cc => {         acc[acc.length] = f(xs[acc.length]);         return acc.length < xs.length ? cc(acc)(rec) : acc;     }      return cc(rec([])(rec)); }  mapc(inc)(xs)(console.log.bind(console)); // [2,3,4,5,6]

instead of cc(acc)(rec) have wrote rec(acc). conclusion correct, tail recursion merely special case of cps , mapc written var rec = acc => {...} proper cps function?

i'd write thing in pure cps following:

const inc = x => cont => cont(x+1);  const map = f => xss => cont => {     if (!xss.length) cont([]);     else f(xss[0])(x => map(f)(xss.slice(1))(xs => cont([x].concat(xs)))); };  // or accumulator: const mapa = f => xs => cont => {     const rec = acc => {         if (acc.length >= xs.length) cont(acc);         else f(xs[acc.length])(x => {             acc.push(x);             rec(acc);         });     }     rec([]); };

is tail recursion merely special case of cps?

i wouldn't so. cps isn't related recursion @ all.
however, cps consists of tail calls, makes stack superfluous - , functions powerful.


Comments

Post a Comment

Popular posts from this blog

Hatching array of circles in AutoCAD using c# -

-
i beginner in autocad plugins .i have created array of circle using following code. now, have hatch circles in array .how that??how hatch circles @ once? moreover, how can return hatch method , use hatch objects.sorry language.thanks in advance. [assembly: commandclass(typeof(beamsection.class1))] namespace beamsection { public class class1 { //class1 obj = new class1(); [commandmethod("beamatsupport")] public void addlightweightpolyline() { // current document , database document acdoc = application.documentmanager.mdiactivedocument; database accurdb = acdoc.database; promptpointresult ppr = acdoc.editor.getpoint("\nselect starting point "); var ucs = acdoc.editor.currentusercoordinatesystem; point3d startingpt = ppr.value.transformby(ucs); list<double> radius = new list<double>(); radius.add(0.5);
Read more

ios - UITEXTFIELD InputView Uipicker not working in swift -

-
hello trying pop uipickerview view programmatically when user clicks on textfield. have tried doesn't doing anything. isn't working. nothing happening when click textfield class userprofiletableviewcontroller: uitableviewcontroller,uitextfielddelegate,uipickerviewdelegate,uipickerviewdatasource { var itempicker: uipickerview! = uipickerview() @iboutlet weak var gendertxtfield: uitextfield! var gender = ["male","female"] override func viewdidload() { super.viewdidload() gendertxtfield.delegate = self itempicker!.delegate = self itempicker!.datasource = self itempicker!.backgroundcolor = uicolor.blackcolor() self.gendertxtfield.inputview = itempicker } func numberofcomponentsinpickerview(pickerview: uipickerview) -> int{ return 1 } // returns # of rows in each component.. func pickerview(pickerview: uipickerview, numberofrowsincomponent component:
Read more

Python Pig Latin Translator -

-
so have been working on @ codecademy.com while trying learn python. don't know if blind , can't see why won't work or what. here's code won't let me use. function print variable if had typed in , print "empty" if didn't type anything. print "welcome english pig latin translator!" original = raw_input("what's name?") if len(original) > 0 print original else print "empty" if len(original) > 0 else the above lines contains syntax errors. try: if len(original) > 0: else: note added colons, ( : ).
Read more