Extract common utility functions

.all-contributorsrc

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+{
+  "files": [
+    "README.md"
+  ],
+  "imageSize": 100,
+  "commit": false,
+  "contributors": [
+    {
+      "login": "sandstreamdevelopment",
+      "name": "sandstreamdevelopment",
+      "avatar_url": "https://avatars2.githubusercontent.com/u/44231396?v=4",
+      "profile": "https://github.com/sandstreamdevelopment",
+      "contributions": [
+        "business",
+        "financial",
+        "ideas"
+      ]
+    }
+  ],
+  "contributorsPerLine": 7,
+  "projectName": "std",
+  "projectOwner": "sandstreamdev",
+  "repoType": "github",
+  "repoHost": "https://github.com"
+}

.gitignore

@@ -59,3 +59,6 @@ typings/
 
 # next.js build output
 .next
+
+index.cjs.js
+index.umd.js

.npmignore

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+regenerate.js

README.md

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-# std
+# std
+
+[![All Contributors](https://img.shields.io/badge/all_contributors-1-orange.svg?style=flat-square)](#contributors)
+
+## Contributors ✨
+
+Thanks goes to these wonderful people ([emoji key](https://allcontributors.org/docs/en/emoji-key)):
+
+<!-- ALL-CONTRIBUTORS-LIST:START - Do not remove or modify this section -->
+<!-- prettier-ignore -->
+<table>
+  <tr>
+    <td align="center"><a href="https://github.com/sandstreamdevelopment"><img src="https://avatars2.githubusercontent.com/u/44231396?v=4" width="100px;" alt="sandstreamdevelopment"/><br /><sub><b>sandstreamdevelopment</b></sub></a><br /><a href="#business-sandstreamdevelopment" title="Business development">💼</a> <a href="#financial-sandstreamdevelopment" title="Financial">💵</a> <a href="#ideas-sandstreamdevelopment" title="Ideas, Planning, & Feedback">🤔</a></td>
+  </tr>
+</table>
+
+<!-- ALL-CONTRIBUTORS-LIST:END -->
+
+This project follows the [all-contributors](https://github.com/all-contributors/all-contributors) specification. Contributions of any kind welcome!

array/any.js

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+export default xs => xs && xs.length > 0;

array/are.js

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+import is from "./is.js";
+
+export default (...xs) => xs.every(is);

array/difference.js

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+export default (xs, ys) => {
+  const zs = new Set(ys);
+
+  return xs.filter(x => !zs.has(x));
+};

array/differs.js

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+export default (xs, ys) =>
+  (!xs && ys) ||
+  (!ys && xs) ||
+  xs.length !== ys.length ||
+  xs.some((x, index) => x !== ys[index]);

array/duplicates.js

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+export default xs =>
+  xs.filter((value, index, self) => self.indexOf(value) !== index);

array/empty.js

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+export default [];

array/exact.js

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+import range from "./range.js";
+
+export default n => xs => range(n).map(index => xs[index]);

array/except.js

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+export default y => xs => xs.filter(x => x !== y);

array/filterInPlace.js

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+export default f => xs => {
+  let i = 0;
+  let j = 0;
+
+  while (i < xs.length) {
+    const value = xs[i];
+    if (f(value, i, xs)) {
+      xs[j++] = value;
+    }
+    i++;
+  }
+
+  xs.length = j;
+  return xs;
+};

array/find.js

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+export default (predicate, fallback) => xs => {
+  const target = xs.find(predicate);
+  return target !== undefined ? target : fallback;
+};

array/first.js

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+export default ([x]) => x;

array/flatMap.js

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+export default f => xs => xs.reduce((ys, y) => ys.concat(f(y)), []);

array/flatten.js

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+export default xs => [].concat(...xs);

array/index.js

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+import any from "./any.js";
+import are from "./are.js";
+import difference from "./difference.js";
+import differs from "./differs.js";
+import duplicates from "./duplicates.js";
+import empty from "./empty.js";
+import exact from "./exact.js";
+import except from "./except.js";
+import filterInPlace from "./filterInPlace.js";
+import find from "./find.js";
+import first from "./first.js";
+import flatMap from "./flatMap.js";
+import flatten from "./flatten.js";
+import intersection from "./intersection.js";
+import is from "./is.js";
+import last from "./last.js";
+import lengthDiffers from "./lengthDiffers.js";
+import map from "./map.js";
+import midpoint from "./midpoint.js";
+import minMax from "./minMax.js";
+import multiple from "./multiple.js";
+import none from "./none.js";
+import partition from "./partition.js";
+import range from "./range.js";
+import repeat from "./repeat.js";
+import reverse from "./reverse.js";
+import reverseIf from "./reverseIf.js";
+import rotate from "./rotate.js";
+import second from "./second.js";
+import secondToLast from "./secondToLast.js";
+import shift from "./shift.js";
+import shuffle from "./shuffle.js";
+import shuffleInPlace from "./shuffleInPlace.js";
+import single from "./single.js";
+import sort from "./sort.js";
+import sum from "./sum.js";
+import transpose from "./transpose.js";
+import unique from "./unique.js";
+import zip from "./zip.js";
+import zipWith from "./zipWith.js";
+
+export {
+  any,
+  are,
+  difference,
+  differs,
+  duplicates,
+  empty,
+  exact,
+  except,
+  filterInPlace,
+  find,
+  first,
+  flatMap,
+  flatten,
+  intersection,
+  is,
+  last,
+  lengthDiffers,
+  map,
+  midpoint,
+  minMax,
+  multiple,
+  none,
+  partition,
+  range,
+  repeat,
+  reverse,
+  reverseIf,
+  rotate,
+  second,
+  secondToLast,
+  shift,
+  shuffle,
+  shuffleInPlace,
+  single,
+  sort,
+  sum,
+  transpose,
+  unique,
+  zip,
+  zipWith
+};
+
+export default {
+  any,
+  are,
+  difference,
+  differs,
+  duplicates,
+  empty,
+  exact,
+  except,
+  filterInPlace,
+  find,
+  first,
+  flatMap,
+  flatten,
+  intersection,
+  is,
+  last,
+  lengthDiffers,
+  map,
+  midpoint,
+  minMax,
+  multiple,
+  none,
+  partition,
+  range,
+  repeat,
+  reverse,
+  reverseIf,
+  rotate,
+  second,
+  secondToLast,
+  shift,
+  shuffle,
+  shuffleInPlace,
+  single,
+  sort,
+  sum,
+  transpose,
+  unique,
+  zip,
+  zipWith
+};

array/intersection.js

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+export default (xs, ys) => xs.filter(value => ys.includes(value));

array/is.js

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+export default value => Array.isArray(value);

array/last.js

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+export default xs => xs[xs.length - 1];

array/lengthDiffers.js

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+export default (a, b) => a.length !== b.length;

array/map.js

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+export default (...fs) => {
+  const f = x => fs.reduce((x, f) => f(x), x);
+  return x => x.map(f);
+};

array/midpoint.js

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+export default xs => xs[Math.floor(xs.length / 2)];

array/minMax.js

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+const { max, min } = Math;
+
+export default ([head, ...tail]) =>
+  tail.reduce(([min, max], current) => [min(min, current), max(max, current)], [
+    head,
+    head
+  ]);

array/multiple.js

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+export default xs => xs.length > 1;

array/none.js

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+import any from "./any.js";
+
+export default xs => !any(xs);

array/partition.js

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+export default predicate => xs =>
+  xs.reduce(
+    ([left, right], current) => {
+      const pass = predicate(current);
+      return pass ? [left, [...right, current]] : [[...left, current], right];
+    },
+    [[], []]
+  );

array/range.js

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+export default n =>
+  Array(n)
+    .fill()
+    .map((_, index) => index);

array/repeat.js

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+export default n => value => Array(n).fill(value);

array/reverse.js

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+export default xs => [...xs].reverse();

array/reverseIf.js

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+import reverse from "./reverse.js";
+
+export default predicate => xs => (predicate ? reverse(xs) : xs);

array/rotate.js

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+export default array => angle => {
+  const margin = Math.PI / 8;
+  const angleWithMargin = angle + margin;
+  const unit = Math.PI / 4;
+  const ratio = angleWithMargin / unit;
+  const offset = Math.floor(ratio);
+  return shift(offset)(array);
+};

array/second.js

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+export default ([, x]) => x;

array/secondToLast.js

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+export default xs => xs[xs.length - 2];

array/shift.js

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+export default n => xs =>
+  xs.map((_, index) => xs[(index + (n % xs.length) + xs.length) % xs.length]);

array/shuffle.js

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+import shuffleInPlace from "./shuffleInPlace.js";
+
+export default xs => shuffleInPlace([...xs]);

array/shuffleInPlace.js

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+export default xs => {
+  for (let i = 0; i < xs.length; i++) {
+    const j = Math.floor(Math.random() * (i + 1));
+    [xs[i], xs[j]] = [xs[j], xs[i]];
+  }
+
+  return xs;
+};

array/single.js

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+export default xs => xs.length === 1;

array/sort.js

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+export default f => xs => [...xs].sort(f);

array/sum.js

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+const add = (a, b) => a + b;
+
+export default xs => xs.reduce(add, 0);

array/transpose.js

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+export default xs => Object.keys(xs[0]).map(key => [xs.map(x => x[key]), key]);

array/unique.js

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+export default xs => [...new Set(xs)];

array/zip.js

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+import zipWith from "./zipWith.js";
+
+export default zipWith((x, y) => [x, y]);

array/zipWith.js

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+export default f => (xs, ys) => xs.map((x, index) => f(x, ys[index]));

async/debounce.js

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+export default (f, wait) => {
+  let timeout;
+
+  return (...args) => {
+    const resolve = () => {
+      timeout = null;
+
+      f(...args);
+    };
+
+    clearTimeout(timeout);
+
+    timeout = setTimeout(resolve, wait);
+  };
+};

async/delay.js

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+export default duration =>
+  new Promise(resolve => setTimeout(resolve, duration));

async/index.js

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+import debounce from "./debounce.js";
+import delay from "./delay.js";
+import sequence from "./sequence.js";
+
+export { debounce, delay, sequence };
+
+export default { debounce, delay, sequence };

async/sequence.js

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+export default async tasks => {
+  const results = tasks.map(_ => undefined);
+
+  await tasks.reduce((chain, current, i) => {
+    return chain.then(() =>
+      current().then(x => {
+        results[i] = x;
+        return x;
+      })
+    );
+  }, Promise.resolve());
+
+  return results;
+};

date/byDateWithFallback.js

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+export default now => (
+  { endedAt: aEnd, startedAt: aStart },
+  { endedAt: bEnd, startedAt: bStart }
+) => {
+  const aEndDate = new Date(aEnd || now);
+  const aStartDate = new Date(aStart || now);
+  const bEndDate = new Date(bEnd || now);
+  const bStartDate = new Date(bStart || now);
+  const aEndDateValue = aEndDate.valueOf();
+  const aStartDateValue = aStartDate.valueOf();
+  const bEndDateValue = bEndDate.valueOf();
+  const bStartDateValue = bStartDate.valueOf();
+
+  const startDateDifference = aStartDateValue - bStartDateValue;
+  const startDatesEqual = startDateDifference === 0;
+
+  return startDatesEqual ? aEndDateValue - bEndDateValue : startDateDifference;
+};