raganwald

const just =
  target =>
    input =>
      input.startsWith(target) &&
      target;

const cases =
  (...patterns) =>
    input => {
      const matches = patterns.map(p => p(input)).filter(m => m !== false);

raganwald

//
// http://raganwald.com/2019/01/14/structural-sharing-and-copy-on-write.html
// http://raganwald.com/2019/01/26/reduce-reuse-recycle.html
//

const SliceHandler = {
  has (slice, property) {
    if (property in slice) {
      return true;
    }

raganwald

const ComposableCarCdr = {
  has (target, name) {
    if (name in target) {
      return true;
    }
    
    if (name === Symbol.isConcatSpreadable) {
      return true;
    }
    

raganwald

function scoop(before, fromPit) {
  const after = before.slice(0);
  const seedsInHand = after[fromPit];
  
  after[fromPit] = 0;
  
  return [after, seedsInHand];
}

function nextPit(pit) {

raganwald

function isBalancedSimple (before) {
  if (before === '') return true;
  
  const after = before.replace('()','');
  
  return (before !== after) && isBalancedSimple(after);
}

function isBalancedMultiple (before) {
  if (before === '') return true;

raganwald

// Prelude: Composeable Functional Pattern Matchers

const just =
  target =>
    input =>
      input.startsWith(target) &&
      target;

const cases =
  (...patterns) =>

raganwald

// Computes the twelve "fundamental" solutions to the eight queens problem
// by filtering the results of the "half-inductive" algorithm.
//
// see http://raganwald.com/2018/08/03/eight-queens.html
//
// search space: 2,750 candidate positions

function testDiagonals (queens) {
  const nesw = [".", ".", ".", ".", ".", ".", ".", ".", ".", ".", ".", ".", ".", ".", "."];
  const nwse = [".", ".", ".", ".", ".", ".", ".", ".", ".", ".", ".", ".", ".", ".", "."];

raganwald

#Denumerable

# Copyright 2002 Reginald Braithwaite-Lee. All Rights Reserved.
# http://www.braithwaite-lee.com/tips/denumerables.html

module Denumerable
  
  #must define :denumerableIteratorFactory, :denumerableIteratorFactory=
  #initialize must support NO ARGUMENTS

raganwald

// A state machine that works from a description including explicit transitions,
// and can generate a transition map and a digraph

const STATES = Symbol("states");
const STARTING_STATE = Symbol("starting-state");
const TRANSITIONS = Symbol("transitions");
const RESERVED = [STARTING_STATE, TRANSITIONS];

const MACHINES_TO_CURRENT_STATE_NAMES = new WeakMap();
const MACHINES_TO_STARTING_STATES = new WeakMap();

raganwald

function * multiplesOf (startingWith, n) {
  let number = startingWith;
  
  while (true) {
    yield number;
    number = number + n;
  }
}

function destructure (iterable) {