♻️ refactor(count/sequence): Improve API.

Author: make-github-pseudonymous-again

README.md

@@ -22,8 +22,16 @@ See [docs](https://aureooms.github.io/js-set-partition/index.html).
 > [regenerator-runtime/runtime](https://www.npmjs.com/package/regenerator-runtime).
 
 ```js
+import {
+	enumerate,
+	count,
+	_count,
+	sequence,
+	_sequence,
+	isPartition
+} from '@aureooms/js-set-partition';
+
 import {range, map} from '@aureooms/js-itertools';
-import {enumerate, count, sequence, isPartition} from '@aureooms/js-set-partition';
 
 enumerate(range(0)); // []
 enumerate(range(1)); // [[0]]
@@ -38,10 +46,11 @@ count(5); // 52n
 count(6); // 203n
 count(26); // 49631246523618756274n
 
-_count(6); // 203
-_count(26); // ???
+_count(1,6); // 203
+_count(1,26); // ???
 
 sequence(); // 1n 1n 2n 3n 5n 15n 52n 203n ...
+_sequence(1); // 1 1 2 3 5 15 52 203 ...
 
 isPartition(range(5), [range(5)]); // true
 isPartition(range(5), map(x => [x], range(5))); // true
@@ -66,8 +75,6 @@ isPartition(range(5), [[5], [0], [1], [2], [3], [4]]); // false
 [![Code issues](https://img.shields.io/codeclimate/issues/aureooms/js-set-partition.svg)](https://codeclimate.com/github/aureooms/js-set-partition/issues)
 [![Code maintainability](https://img.shields.io/codeclimate/maintainability/aureooms/js-set-partition.svg)](https://codeclimate.com/github/aureooms/js-set-partition/trends/churn)
 [![Code coverage (cov)](https://img.shields.io/codecov/c/gh/aureooms/js-set-partition/main.svg)](https://codecov.io/gh/aureooms/js-set-partition)
-<!--[![Code coverage (alls)](https://img.shields.io/coveralls/github/aureooms/js-set-partition/main.svg)](https://coveralls.io/r/aureooms/js-set-partition)-->
-<!--[![Code coverage (clim)](https://img.shields.io/codeclimate/coverage/aureooms/js-set-partition.svg)](https://codeclimate.com/github/aureooms/js-set-partition/trends/test_coverage_new_code)-->
 [![Code technical debt](https://img.shields.io/codeclimate/tech-debt/aureooms/js-set-partition.svg)](https://codeclimate.com/github/aureooms/js-set-partition/trends/technical_debt)
 [![Documentation](https://aureooms.github.io/js-set-partition/badge.svg)](https://aureooms.github.io/js-set-partition/source.html)
 [![Package size](https://img.shields.io/bundlephobia/minzip/@aureooms/js-set-partition)](https://bundlephobia.com/result?p=@aureooms/js-set-partition)

src/_count.js

@@ -0,0 +1,6 @@
+import {nth} from '@aureooms/js-itertools';
+
+import _sequence from './_sequence';
+
+const _count = (init, k) => nth(_sequence(init), k);
+export default _count;

src/_sequence.js

@@ -0,0 +1,16 @@
+export default function* _sequence(init) {
+	yield init;
+	const a = [init];
+	while (true) {
+		const n = a.length;
+		let current = a[n - 1];
+		yield current;
+		for (let i = 0; i < n; ++i) {
+			const next = current + a[i];
+			a[i] = current;
+			current = next;
+		}
+
+		a.push(current);
+	}
+}

src/count.js

@@ -1,6 +1,4 @@
-import {nth} from '@aureooms/js-itertools';
+import _count from './_count';
 
-import sequence from './sequence';
-
-const count = (k) => nth(sequence(), k);
+const count = (k) => _count(1n, k);
 export default count;

src/index.js

@@ -1,16 +1,20 @@
+import _count from './_count';
 import _enumerate from './_enumerate';
+import _sequence from './_sequence';
 import count from './count';
 import enumerate from './enumerate';
 import isPartition from './isPartition';
 import sequence from './sequence';
 
 /* eslint import/no-anonymous-default-export: [2, {"allowObject": true}] */
 export default {
+	_count,
 	_enumerate,
+	_sequence,
 	count,
 	enumerate,
 	isPartition,
 	sequence,
 };
 
-export {_enumerate, count, enumerate, isPartition, sequence};
+export {_count, _enumerate, _sequence, count, enumerate, isPartition, sequence};

src/sequence.js

@@ -1,16 +1,4 @@
-export default function* sequence() {
-	yield 1n;
-	const a = [1n];
-	while (true) {
-		const n = a.length;
-		let current = a[n - 1];
-		yield current;
-		for (let i = 0; i < n; ++i) {
-			const next = current + a[i];
-			a[i] = current;
-			current = next;
-		}
+import _sequence from './_sequence';
 
-		a.push(current);
-	}
-}
+const sequence = () => _sequence(1n);
+export default sequence;

test/src/count.js

@@ -1,6 +1,6 @@
 import test from 'ava';
 
-import {count} from '../../src';
+import {count, _count} from '../../src';
 
 const macro = (t, k, Bk) => {
 	t.is(count(k), Bk);
@@ -16,3 +16,17 @@ test(macro, 4, 15n);
 test(macro, 5, 52n);
 test(macro, 6, 203n);
 test(macro, 26, 49631246523618756274n);
+
+const _macro = (t, k, Bk) => {
+	t.is(_count(1, k), Bk);
+};
+
+_macro.title = (title, k, Bk) => `_count(1, ${k}) = ${Bk}`;
+
+test(_macro, 0, 1);
+test(_macro, 1, 1);
+test(_macro, 2, 2);
+test(_macro, 3, 5);
+test(_macro, 4, 15);
+test(_macro, 5, 52);
+test(_macro, 6, 203);

test/src/isPartition.js

@@ -4,32 +4,90 @@ import {iter, range, list, map} from '@aureooms/js-itertools';
 
 import {isPartition} from '../../src';
 
-const macro = (t, n, partition, is) => {
-	t.is(isPartition(range(n), partition), is, 'partition');
-	t.is(isPartition(range(n), map(iter, partition)), is, 'map(iter, partition)');
+const macro = (t, set, partition, is) => {
+	t.is(isPartition(set, partition), is, 'isPartition(set, partition)');
+
+	t.is(
+		isPartition(set, map(iter, partition)),
+		is,
+		'isPartition(set, map(iter, partition))',
+	);
+
+	t.is(
+		isPartition(set, list(map(iter, partition))),
+		is,
+		'isPartition(set, list(map(iter, partition)))',
+	);
+
+	t.is(
+		isPartition(set, list(map((x) => x, partition))),
+		is,
+		'isPartition(set, list(map((x) => x, partition)))',
+	);
+
+	t.is(
+		isPartition(iter(set), partition),
+		is,
+		'isPartition(iter(set), partition)',
+	);
+
+	t.is(
+		isPartition(iter(set), map(iter, partition)),
+		is,
+		'isPartition(iter(set), map(iter, partition))',
+	);
+
 	t.is(
-		isPartition(range(n), list(map(iter, partition))),
+		isPartition(iter(set), list(map(iter, partition))),
 		is,
-		'list(map(iter, partition))',
+		'isPartition(iter(set), list(map(iter, partition)))',
 	);
+
 	t.is(
-		isPartition(range(n), list(map((x) => x, partition))),
+		isPartition(iter(set), list(map((x) => x, partition))),
 		is,
-		'list(map(x => x, partition))',
+		'isPartition(iter(set), list(map((x) => x, partition)))',
 	);
 };
 
-macro.title = (title, n, partition, is) =>
-	`isPartition(${n}, ${JSON.stringify(partition)} = ${is})`;
+macro.title = (title, set, partition, is) =>
+	`isPartition(${JSON.stringify(set)}, ${JSON.stringify(partition)} = ${is})`;
+
+const yea = (t, set, partition) => macro(t, set, partition, true);
+yea.title = (title, set, partition) => macro.title(title, set, partition, true);
+
+const nay = (t, set, partition) => macro(t, set, partition, false);
+nay.title = (title, set, partition) =>
+	macro.title(title, set, partition, false);
+
+const _5 = list(range(5));
+
+test(yea, _5, [[0, 1, 2, 3, 4]]);
+test(yea, _5, [[0], [1], [2], [3], [4]]);
+test(yea, _5, [[0, 1], [2], [3], [4]]);
+test(yea, _5, [[2, 1], [3], [0, 4]]);
+
+test(nay, _5, [[], [0], [1], [2], [3], [4]]);
+test(nay, _5, [[0], [0], [1], [2], [3], [4]]);
+test(nay, _5, [[5], [0], [1], [2], [3], [4]]);
+test(nay, _5, [[-1], [0], [1], [2], [3], [4]]);
+test(nay, _5, [[2 ** 53 - 1], [0], [1], [2], [3], [4]]);
+test(nay, _5, [[-(2 ** 53)], [0], [1], [2], [3], [4]]);
+
+// From Wikipedia: https://en.wikipedia.org/wiki/Partition_of_a_set#Examples
+const _3 = [1, 2, 3];
 
-test(macro, 5, [[0, 1, 2, 3, 4]], true);
-test(macro, 5, [[0], [1], [2], [3], [4]], true);
-test(macro, 5, [[0, 1], [2], [3], [4]], true);
-test(macro, 5, [[2, 1], [3], [0, 4]], true);
+// The set { 1, 2, 3 } has these five partitions (one partition per item):
+test(yea, _3, [[1], [2], [3]]);
+test(yea, _3, [[1, 2], [3]]);
+test(yea, _3, [[1, 3], [2]]);
+test(yea, _3, [[1], [2, 3]]);
+test(yea, _3, [[1, 2, 3]]);
 
-test(macro, 5, [[], [0], [1], [2], [3], [4]], false);
-test(macro, 5, [[0], [0], [1], [2], [3], [4]], false);
-test(macro, 5, [[5], [0], [1], [2], [3], [4]], false);
-test(macro, 5, [[-1], [0], [1], [2], [3], [4]], false);
-test(macro, 5, [[2 ** 53 - 1], [0], [1], [2], [3], [4]], false);
-test(macro, 5, [[-(2 ** 53)], [0], [1], [2], [3], [4]], false);
+// The following are not partitions of { 1, 2, 3 }:
+test(nay, _3, [[], [1, 3], [2]]);
+test(nay, _3, [
+	[1, 2],
+	[2, 3],
+]);
+test(nay, _3, [[1], [2]]);

test/src/sequence.js

@@ -2,10 +2,16 @@ import test from 'ava';
 
 import {list, take} from '@aureooms/js-itertools';
 
-import {sequence} from '../../src';
+import {sequence, _sequence} from '../../src';
 
-test('sequence', (t) => {
-	const n = 7;
+test('sequence()', (t) => {
 	const expected = [1n, 1n, 2n, 5n, 15n, 52n, 203n];
+	const n = expected.length;
 	t.deepEqual(list(take(sequence(), n)), expected);
 });
+
+test('_sequence(1)', (t) => {
+	const expected = [1, 1, 2, 5, 15, 52, 203];
+	const n = expected.length;
+	t.deepEqual(list(take(_sequence(1), n)), expected);
+});