venil7

const useThunk = (reducer, initState) => {
  const [state, dispatch] = useReducer(reducer, initState);
  const thunkDispatch = action => {
    if (typeof action === "function") {
      action(dispatch, () => state);
    } else {
      dispatch(action);
    }
  };
  return [state, thunkDispatch];

venil7

const merge = (a: number[], b: number[]): number[] => {
  let length = a.length + b.length;
  let result = Array(length);
  let i = 0, j = 0, k = 0;
  while (i < a.length && j < b.length) {
    if (a[i] < b[j]) {
      result[k] = a[i];
      i += 1;
    } else if (a[i] > b[j]) {
      result[k] = b[j]

venil7

let pairs = (arr: number[], s: number): number[][] => {
  let cache = {};
  let res = [];
  for (let i of arr) {
    if (!cache[i]) {
      cache[i] = true;
    }
    let snd = s - i;
    if (cache[snd]) {
      res.push([i, snd]);

venil7

type state = {a: int};
type action =
  | Remove
  | Add
  | Update;

let component = ReasonReact.reducerComponent("ReducerComponent");
let make = _children => {
  ...component,
  initialState: () => 1,

venil7

class Maybe<T> {
  constructor(private val: T) { }
  with<Z>(f: (z: T) => Z): Maybe<Z> {
    return new Maybe(this.return(f));
  }
  return<Z>(f: (z: T) => Z): Z {
    try {
      return (f(this.val));
    } catch (err) {
      return undefined;

venil7

const aux = (f: (a,b) => number, acc: number) => 
  (n?: number) => (n !== undefined) ? aux(f, f(acc, n)) : acc;

const add = (a, b) => a + b;
const mul = (a, b) => a * b;

const sum = aux(add, 0);
const product = aux(mul, 1);

const sum1 = sum(2)(3)(5)(); //10

venil7

class ReaderMonad<A, B> {
  constructor(public runReader: (a: A) => B) {
  }

  bind<C>(func: (b: B) => ReaderMonad<A, C>): ReaderMonad<A, C> {
    return new ReaderMonad<A, C>((a: A) => {
      const b = this.runReader(a);
      return func(b).runReader(a);
    });
  }

venil7

class StateMonad<S, A> {
  constructor(public runState: (s: S) => ({ s: S, a: A })) {
  }

  static return_<S, A>(a: A): StateMonad<S, A> {
    return new StateMonad(s => ({ s, a }));
  }

  bind<B>(func: (a: A) => StateMonad<S, B>): StateMonad<S, B> {
    return new StateMonad<S, B>((s: S) => {

venil7

let next = (seq: list(int)) : int =>
  switch (seq) {
  | [] => 0
  | [0] => 1
  | [x, y, ..._] => x + y
  };

let fib = (n: int) : list(int) => {
  let rec fib' = (m: int, seq: list(int)) : list(int) =>
    switch (m) {

venil7

type rod = list(int);

exception InvalidMove(int, int);

exception OtherMove(rod, rod);

let moveRods = (a: rod, b: rod) : (rod, rod) =>
  switch (a, b) {
  | ([x, ...xs], []) => (xs, [x])
  | ([x, ...xs], [y, ...ys]) when x < y => (xs, [x, y, ...ys])