package lablqml

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OCamlfind package and PPX extension to interface OCaml and QtQuick


Dune Dependency






Versions <= 0.4 are known as lablqt, >0.5 -- as lablqml.


gui ui qt

Published: 02 Jul 2021


Let's write QML/QtQuick GUI for OCaml (or Reason) using lablqml!

In this repo you can find my work about integrating OCaml and Qt. Initially, I planned to generate binding code for OCaml and Qt Widgets and called this library lablqt. But I found it hard to implement mostly because Qt relies on inheritance very much (we can't add onClick handler for button without inheritance). Later I decided to generate binding code for OCaml and QML/QtQuick. And I believe that QtQuick is the right way to create UI in Qt right now. See online book for getting started with Qt/QML itself

From 14th of February 2017 it's renamed from lablqt to lablqml because it is actually about QtQuick and not QtWidgets or Qt itself. If you really need QtWidgets you can check out mrvn's work or def's.

Directories mapping:

  • PPX syntax extension with code generator is in ppx/.

  • Library for interfacing with QtQuick 2 is in lib.

  • Demo that can be build during opam installation is in dune_test. Use make demo to build it.

  • Old demos that are not using dune as build system are in demos/.

  • Demo app qocamlbrowser (ocamlbrowser with QtQuick instead of Tcl/Tk) is located in separate repo.

Github pages site and tutorial are available.

Use ./configure && make to build it. Don't forget to install g++ and good Qt version (>= 5.3 I think, ./configure will check for it, btw).

Installed files

$ opam show lablqml --list-files

There is a library here. It's fine to use it for simple programs

There is also ppx_qt executable. It is used to generate C++ code from OCaml. See demos/ for examples

Minimal ocamlfind-based helloworld

➜  cat
open Lablqml

let main () = ()
let () =
  run_with_QQmlApplicationEngine Sys.argv main "Root.qml"
➜  cat Root.qml
import QtQuick 2.0
import QtQuick.Controls 1.0

ApplicationWindow {
    color: "#FFFFDF" // we declare rectangle with custom background color
    width:  400;
    height: 300;     // with custom size
    Text {
        anchors.centerIn: parent
        text: "Click me!"
    MouseArea {
        anchors.fill: parent      // all space in parent Rectangle will be clickable
➜  ocamlfind opt -package lablqml -thread -linkpkg -cclib -lQt5Quick -cclib -lQt5Qml -cclib -lQt5Network -cclib -lQt5Widgets -cclib -lQt5Gui -cclib -lQt5Core -cclib -lstdc++
➜  ./a.out

Playing with REPL

#require "lablqml";;

Dev Dependencies


Used by (1)

  1. qocamlbrowser < "0.2.8" | >= "0.2.12"




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