demo.js

// Generated by BUCKLESCRIPT VERSION 1.7.5, PLEASE EDIT WITH CARE
'use strict';


function counter(state, action) {
  var match = action.type;
  switch (match) {
    case 0 : 
        return state + 1 | 0;
    case 1 : 
        return state - 1 | 0;
    case 2 : 
        return state + 2 | 0;
    
  }
}

function bump_counter() {
  return {
          type: /* Increment */0
        };
}

var increment = /* Increment */0;

var decrement = /* Decrement */1;

var somethingElse = /* SomethingElse */2;

exports.increment     = increment;
exports.decrement     = decrement;
exports.somethingElse = somethingElse;
exports.counter       = counter;
exports.bump_counter  = bump_counter;
/* No side effect */

demo.re

type actions =
  | Increment
  | Decrement
  | SomethingElse
[@@bs.deriving {accessors: accessors}];

let counter ::state ::action =>
  switch action##_type {
  | Increment => state + 1
  | Decrement => state - 1
  | SomethingElse => state + 2
  };

let bump_counter () => {"_type": Increment};