f# - How to write an infix function -


is there way write infix function not using symbols? this:

let mod x y = x % y x mod y

maybe keyword before "mod" or something.

the existing answer correct - cannot define infix function in f# (just custom infix operator). aside trick pipe operators, can use extension members:

// define extension member 'modulo'  // can called on int32 value type system.int32   member x.modulo n = x % n  // use it, can write this: 10 .modulo 3

note space before . needed, because otherwise compiler tries interpret 10.m numeric literal (like 10.0f).

i find bit more elegant using pipeline trick, because f# supports both functional style , object-oriented style , extension methods - in sense - close equivalent implicit operators functional style. pipeline trick looks slight misuse of operators (and may confusing @ first - perhaps more confusing method invocation).

that said, have seen people using other operators instead of pipeline - perhaps interesting version 1 (which uses fact can omit spaces around operators):

// define custom operators make syntax prettier let (</) b = |> b let (/>) b = <| b     let modulo b = % b   // can turn function infix using: 10 </modulo/> 3

but not established idiom in f# world, still prefer extension members.


Comments

Post a Comment

Popular posts from this blog

jquery - How can I dynamically add a browser tab? -

since using iframes house external pages are, accounts "not preferred method" , disallowed sites (flickr, one), want dynamically generate browser tabs. e.g., when user submits form, want dynamically generate tab on browser in response submitted. e.g., might want add new tab url like: http://www.bigsurgarrapata.com/contact how in jquery? you want form target attribute action attribute. http://www.w3schools.com/tags/att_form_target.asp browsers have ultimate control on result of target attribute open new tab value of _blank. <form action="contact_submit.php" target="_blank" method="post">
Read more

keyboard - C++ GetAsyncKeyState alternative -

i using windows.h library's getasynckeystate function define key pushed on keyboard . here program returns int value of pushed key example. #include <iostream> #include <windows.h> using namespace std; int main (){ char i; for(i=8;i<190;i++){ if(getasynckeystate(i)== -32767){ cout<<int (i)<<endl; } } return 0; } but trying make opengl simple game , function appeared slow . there function not need cycle 180 times , if statement . thanks you're trying make opengl game, you're going use glfw. if that's case can away using glfwgetkey() such: if (glfwgetkey(glfw_key_up) == glfw_press) {...} if (glfwgetkey(glfw_key_down) == glfw_press) {...} that method nicely explained in tutorial 6 opengl-tutorial.org . should start first tutorial of beginners tutorials , later intermediate tutorials . if you're going make win32 window can listen wm_keydown or wm_keyup messages , virtua...
Read more

android - java.net.UnknownHostException(Unable to resolve host “URL”: No address associated with hostname) -

i developing app testing asp.net webservice in android.for simple webservice adding 2 numbers used.where numbers passed parameters.the result in dialogue.the webserver works in local. when application runs following result exception.i provided internet permission in manifest. java.net.unknownhostexception(unable resolve host “ http://url.com/ ”: no address associated hostname) my code given below main activity public static string rslt=""; /** called when activity first created. */ @override public void oncreate(bundle savedinstancestate) { super.oncreate(savedinstancestate); setcontentview(r.layout.activity_main); button b1=(button)findviewbyid(r.id.button1); final alertdialog ad=new alertdialog.builder(this).create(); b1.setonclicklistener(new onclicklistener() { @override public void onclick(view arg0) { // todo auto-generated method stub try { ...
Read more