\n\n```typescript\nexpectType
\n\n```javascript\nit('should work on lists', () => {\n filter(greaterThan(2))([1, 2, 3]).should.deep.equal([3]);\n});\n\nit('should work on objects', () => {\n filter(greaterThan(2))({ a: 1, b: 2, c: 3 }).should.deep.equal({ c: 3 })\n});\n\nit('should work on Maps', () => {\n filter('goldMember')(\n new Map(Object.entries(store.byName))\n ).should.deep.equal(new Map([['liz', liz]]));\n});\n\n```\n\n
\n\n\n```typescript\nexpectType
\n\n```javascript\nit('should work on lists', () => {\n map(inc)([1, 2, 3]).should.deep.equal([2, 3, 4])\n});\n\nit('should work on objects', () => {\n map(inc)({ a: 1, b: 2, c: 3 }).should.deep.equal({ a: 2, b: 3, c: 4 })\n})\n\nit('should receive key as second param', () => {\n map((value, key) => value + key)({a: 1}).should.deep.equal({a: '1a'})\n})\n\nit('should work on maps', () => {\n const input = new Map([['a', 1], ['b', 2], ['c', 3]])\n const output = new Map([['a', 2], ['b', 3], ['c', 4]])\n map(inc)(input).should.deep.equal(output)\n})\n\nit('should work on sets', () => {\n const input = new Set([1, 2, 3])\n const output = new Set([2, 3, 4])\n map(inc)(input).should.deep.equal(output)\n})\n\nit('should work on promises', () => {\n const p = Promise.resolve({a: 1})\n return map('a')(p).should.eventually.equal(1)\n})\n\nit('should work with shorthand', () => {\n map('a')([{ a: 1 }, { a: 2 }, { a: 3 }]).should.deep.equal([1, 2, 3]);\n\n map('a')({ d: { a: 1 }, c: { a: 2 }, e: { a: 3 } }).should.deep.equal({\n d: 1,\n c: 2,\n e: 3\n });\n \n map({ a: 1 })([{ a: 1 }, { a: 2 }, { a: 3 }]).should.deep.equal([\n true,\n false,\n false\n ]);\n});\n\n```\n\n
\n\n\n```typescript\nexpectType
\n\n```javascript\nit('should work on lists', () => {\n find(user => user.isLive)([\n { isLive: true, name: 'jack' }\n ]).name.should.equal('jack');\n find('isLive')([{ isLive: true, name: 'jack' }]).name.should.equal(\n 'jack'\n );\n find({ name: 'jack' })([{ isLive: true, name: 'jack' }]).isLive.should\n .be.true;\n});\n\nit('should work on objects', () => {\n find(user => user.isLive)({\n jack: { isLive: true, name: 'jack' }\n }).name.should.equal('jack');\n find('isLive')({\n jack: { isLive: true, name: 'jack' }\n }).name.should.equal('jack');\n find({ name: 'jack' })({ jack: { isLive: true, name: 'jack' } }).isLive\n .should.be.true;\n});\n\nit('should work on Maps', () => {\n find('goldMember')(\n new Map(Object.entries(store.byName))\n ).should.deep.equal(liz);\n});\n\nit('should work on Sets', () => {\n find('goldMember')(\n new Set(Object.values(store.byName))\n ).should.deep.equal(liz);\n});\n\n```\n\n
\n\n\n```typescript\nexpectType
\n\n```javascript\nit('should work on lists', () => {\n some(user => user.isLive)([\n { isLive: true, name: 'jack' }\n ]).should.be.true\n some('isLive')([{ isLive: true, name: 'jack' }]).should.be.true\n some({ name: 'jack' })([{ isLive: true, name: 'jack' }]).should.be.true\n some({ name: 'john' })([{ isLive: true, name: 'jack' }]).should.be.false\n some(user => user.isLive)([{ isLive: true, name: 'jack' }]).should.be.true\n some(user => !user.isLive)([{ isLive: true, name: 'jack' }]).should.be.false\n});\n\nit('should work on objects', () => {\n some(user => user.isLive)({\n jack: { isLive: true, name: 'jack' }\n }).should.be.true\n some('isLive')({\n jack: { isLive: true, name: 'jack' }\n }).should.be.true\n some({ name: 'jack' })({ jack: { isLive: true, name: 'jack' } }).should.be.true;\n});\n\nit('should work on Maps', () => {\n some('goldMember')(\n new Map(Object.entries(store.byName))\n ).should.be.true\n});\n\nit('should work on Sets', () => {\n some('goldMember')(\n new Set(store.users)\n ).should.be.true\n\n some({name: s => s.includes('z')})(\n new Set(store.users)\n ).should.be.true\n\n some({name: s => s.includes('x')})(\n new Set(store.users)\n ).should.be.false\n});\n\n```\n\n
\n\n\n```typescript\nexpectType
\n\n```javascript\nit('should concat lists', () => {\n cons(1)([1, 2, 3]).should.deep.equal([1, 2, 3, 1]);\n expect(() => cons(1)(2)).to.throw(\n 'Invalid attempt to spread non-iterable instance'\n );\n});\n\n```\n\n
\n\n\n```typescript\nexpectType
\n\n```javascript\nit('should prepend items to a list', () => {\n unshift(1)([1, 2, 3]).should.deep.equal([1, 1, 2, 3]);\n expect(() => unshift(1)(2)).to.throw(\n 'Invalid attempt to spread non-iterable instance'\n );\n});\n\n```\n\n
\n\n\n```typescript\nexpectType
\n\n```javascript\nit('should extract the first element', () => {\n first([1, 2, 3]).should.equal(1);\n first('hello').should.equal('h');\n should.not.exist(first([]));\n});\n\n```\n\n
\n\n\n```typescript\nexpectType
\n\n```javascript\nit('should extract the tail', () => {\n rest([1, 2, 3]).should.deep.equal([2, 3]);\n rest([]).should.deep.equal([]);\n});\n\n```\n\n
\n\n\n```typescript\nexpectType
\n\n```javascript\nit('should concatenate lists in reverse order', () => {\n concat([1, 2, 3])([2, 3]).should.deep.equal([2, 3, 1, 2, 3]);\n})\n\n```\n\n
\n\n\n```typescript\nexpectType
\n\n```javascript\nit('should concatenate lists in lexical order', () => {\n prepend([1, 2, 3])([2, 3]).should.deep.equal([1, 2, 3, 2, 3]);\n})\n\n```\n\n
\n\n\n```typescript\nexpectType
\n\n```javascript\nit('should use into to create functions', () => {\n into('a')({ a: 10 }).should.equal(10);\n into({ a: 10 })({ a: 10 }).should.be.true;\n into(x => x + 1)(10).should.equal(11);\n});\n\n```\n\n
\n\n\n```typescript\nexpectType<(obj: HasPattern<{ a: number; }>) => boolean>(has({a: 1}))\nexpectType<(obj: HasPattern<{ a: false; }>) => boolean>(has({a: false}))\nexpectType
\n\n```javascript\nit('should handle multiple patterns and nested keys', () => {\n has({ a: { b: 2 }, c: 3 })({ a: { b: 2, f: 5 }, c: 3, d: 4 }).should.be.true\n});\n\nit('should return false if not true', () => {\n has({ a: { b: 2 }, c: 3 })({ a: { b: 6, f: 5 }, d: 4 }).should.be.false\n});\n\nit('should handle null values', () => {\n has({ a: null })({ a: null }).should.be.true\n});\n\nit('should handle scalars', () => {\n has('three')('three').should.be.true;\n has('three')('four').should.be.false;\n has(true)(true).should.be.true;\n has(false)(false).should.be.true;\n has(true)(false).should.be.false;\n has(undefined)(undefined).should.be.true;\n has(null)(null).should.be.true;\n has(undefined)(null).should.be.false;\n has(3)(3).should.be.true;\n has(3)(4).should.be.false;\n});\n\nit('should handle lists', () => {\n has([1, 2])([1, 2]).should.be.true;\n has({ a: [1, 2] })({ a: [1, 2], b: 3 }).should.be.true;\n});\n\nit('should handle predicate functions', () => {\n has(_.isString)('hello').should.be.true;\n has(_.isString)(5).should.be.false;\n has({ a: _.isString })({ a: 'hello' }).should.be.true;\n has({ a: _.isString })({ a: 5 }).should.be.false;\n has({ a: n => n % 2 == 1, b: { c: _.isString } })({\n a: 5,\n b: { c: 'hello' }\n }).should.be.true;\n has({ a: n => n % 2 == 0, b: { c: _.isString } })({\n a: 5,\n b: { c: 'hello' }\n }).should.be.false\n});\n\nit('should handle unbalanced patterns and objects', () => {\n has({ a: { b: { c: 12 } } })(null).should.be.false;\n has({ a: { b: { c: 12 } } })({ a: { b: null } }).should.be.false;\n});\n\nit('should handle binding', () => {\n const base = {\n IDTag() {\n return this.tag;\n }\n };\n\n const extended = {\n ...base,\n tag: 'hi'\n };\n\n has({ IDTag: returns('hi') })(extended).should.be.true;\n});\n\n```\n\n
\n\n\n```typescript\nexpectType<(b: number) => boolean>(greaterThan(2))\nexpectType<(b: string) => boolean>(greaterThan('a'))\nexpectType
\n\n```javascript\nit('should compare greaterThan', () => {\n greaterThan(2)(3).should.be.true;\n greaterThan(3)(2).should.be.false;\n})\n\nit('should compare strings value', () => {\n greaterThan('a')('b').should.be.true;\n greaterThan('b')('a').should.be.false;\n})\n\n```\n\n
\n\n\n```typescript\nexpectType<(b: number) => boolean>(lessThan(2))\nexpectType<(b: string) => boolean>(lessThan('a'))\nexpectType
\n\n```javascript\nit('should compare lessThan', () => {\n lessThan(2)(3).should.be.false;\n lessThan(3)(2).should.be.true;\n})\n\nit('should compare strings value', () => {\n lessThan('a')('b').should.be.false;\n lessThan('b')('a').should.be.true;\n})\n\n```\n\n
\n\n\n```typescript\nexpectType
\n\n```javascript\nit('should toggle values', () => {\n toggle(true).should.be.false;\n toggle(false).should.be.true;\n})\n\n```\n\n
\n\n\n```typescript\nexpectType
\n\n```javascript\nit('works', () => {\n returns(10)(() => 10).should.be.true;\n returns(7)(() => 10).should.be.false;\n})\n\n\n```\n\n
\n\n\n```typescript\nexpectType<10>(identity(10))\nexpectType<\"butts\">(identity(\"butts\"))\n\n```\n\n
\n\n\n```javascript\nit('just gives stuff back', () => {\n identity(10).should.be.equal(10)\n identity('hi').should.be.equal('hi')\n})\n\n```\n\n
\n\n\n```typescript\ntype Flipped = (b: any) => (a: A) => A\nexpectAssignable
\n\n```javascript\nit('flips argument order', () => {\n flip(lessThan)(3)(9).should.be.true\n flip(sub)(1)(9).should.equal(-8)\n})\n\n```\n\n
\n\n\n```typescript\nexpectType
\n\n```javascript\nit('should be constant', () => {\n const fifteen = always(15)\n fifteen(20).should.be.equal(15)\n fifteen('asdfasdf').should.be.equal(15)\n})\n\n```\n\n
\n\n\n```typescript\ndeclare function notFn1(a: number): string \ndeclare function notFn4(a: number, b: string, c: boolean, d: number): string \nexpectType
\n\n```javascript\nit('should negate functions of various arities', () => {\n const isEven = n => n % 2 == 0\n const plus = (a, b) => a + b\n not(isEven)(3).should.be.true\n not(plus)(2, 3).should.be.false\n not(plus)(2, -2).should.be.true\n})\n\nit('should handle shorthand', () => {\n not('goldMember')(jack).should.be.true\n not({name: 'Jack Sparrow'})(jack).should.be.false\n})\n\n```\n\n
\n\n\n```typescript\ndeclare function andFn1(a: number): number\ndeclare function andFn2(a: number, b: string): number\ndeclare function andFn3(a: number, b: string, c: boolean): number\ndeclare function andFn3Bad(a: number, b: string, c: boolean): boolean\nexpectType
\n\n```javascript\nconst isEven = n => n % 2 == 0;\nconst isPositive = n => n > 0;\nconst plus = (a, b) => a + b\nconst lt = (a, b) => a < b\nconst gt = (a, b) => a > b\n\nit('handles multiple functions', () => {\n and(isEven, isPositive)(4).should.be.true;\n and(isEven, isPositive)(3).should.be.false;\n and(isEven, isPositive)(-1).should.be.false \n})\n\nit('handles functions with different arities', () => {\n and(lt, isEven)(4, 9).should.be.true;\n and(lt, isEven)(4, 9).should.be.true;\n and(lt, isEven)(3, 9).should.be.false;\n})\n\nit('returns the final value or short circuits', () => {\n and(isEven, plus)(4, 9).should.equal(13);\n and(gt, isEven, plus)(3, 9).should.be.false;\n and(lt, sub(3), isEven)(3, 9).should.equal(0);\n})\n\nit('execution stops after a false', () => {\n const boomMsg = 'boom'\n const boom = () => {throw new Error(boomMsg)}\n and(always(false), boom)(false).should.be.false\n expect(() => and(always(true), boom)(false)).throws(boomMsg)\n})\n\n```\n\n
\n\n\n```typescript\ndeclare function orFn1(a: number): number\ndeclare function orFn2(a: number, b: string): number\ndeclare function orFn3(a: number, b: string, c: boolean): number\ndeclare function orFn3Bad(a: number, b: string, c: boolean): boolean\nexpectType
\n\n```javascript\nconst isEven = n => n % 2 == 0;\nconst isPositive = n => n > 0;\nconst plus = (a, b) => a + b\nconst lt = (a, b) => a < b\nconst gt = (a, b) => a > b\n\nit('handles multiple functions', () => {\n or(isEven, isPositive)(4).should.be.true;\n or(isEven, isPositive)(3).should.be.true;\n or(isEven, isPositive)(-1).should.be.false \n})\n\nit('handles functions with different arities', () => {\n or(lt, isEven)(4, 9).should.be.true;\n or(lt, isEven)(4, 9).should.be.true;\n or(lt, isEven)(3, 9).should.be.true;\n or(lt, isEven)(3, 1).should.be.false;\n})\n\nit('returns the final value or short circuits', () => {\n or(isEven, plus)(3, 9).should.equal(12);\n or(gt, isEven, plus)(3, 9).should.equal(12)\n or(lt, sub(3), isEven)(3, 9).should.be.true\n})\n\nit('execution stops after a true', () => {\n const boomMsg = 'boom'\n const boom = () => {throw new Error(boomMsg)}\n or(always(true), boom)(false).should.be.true\n expect(() => or(always(false), boom)(false)).throws(boomMsg)\n})\n\n```\n\n
\n(pat: P): \n\n```typescript\nexpectType \n\n```javascript\nit('fills in keys on an object', () => {\n fill({a: 10})({b: 5}).a.should.equal(10)\n fill({a: 10})({b: 5}).b.should.equal(5)\n fill({a: 10})({a: null}).a.should.equal(10)\n should.not.exist(fill({b: 10})({a: null}).a)\n})\n\nit('should not overwrite existing keys', () => {\n fill({a: 10})({a: 5}).a.should.equal(5)\n fill({a: {b: 10}})({a: 5}).a.should.equal(5)\n})\n\nit('should merge nested keys', () => {\n const out = fill({a: {b: 10, c: 15}})({a: {c: 20}})\n out.a.b.should.be.equal(10)\n out.a.c.should.be.equal(20)\n})\n\nit('should not overwrite falsey values', () => {\n fill({a: 10})({a: false}).a.should.equal(false)\n fill({a: 10})({a: 0}).a.should.equal(0)\n fill({a: 10})({a: ''}).a.should.equal('')\n})\n\n```\n\n \n\n```typescript\nexpectType \n\n```javascript\nit('should find largest elements', () => {\n store.users.reduce(maxOf(user => user.name.length)).should.be.equal(liz)\n jack.posts.reduce(maxOf('likes')).likes.should.be.equal(70)\n})\n\n```\n\n \n\n```typescript\nexpectType \n\n```javascript\nit('finds elements given a pattern', () => {\n store.users.reduce(findOf('name')).should.be.equal(store.users[0])\n store.users.reduce(findOf({name: liz.name})).should.be.equal(liz)\n})\n\n```\n\n \n\n```typescript\nexpectType \n\n```javascript\nit('should sum all elements specified by pattern', () => {\n store.users.reduce(sumOf(user => user.name.length)).should.be.equal(37)\n liz.posts.reduce(sumOf('likes')).should.be.equal(15000)\n})\n\n```\n\n \n\n```typescript\nexpectType \n\n```javascript\nit('should multiply all elements specified by pattern', () => {\n store.users.reduce(productOf(user => user.name.length)).should.be.equal(1848)\n liz.posts.reduce(productOf('likes')).should.be.equal(50000000)\n})\n\n```\n\n \n\n```typescript\nexpectType \n\n```javascript\nit(\"is an accessor\", () => {\n get('name')(jack).should.equal('Jack Sparrow')\n})\n\nit(\"is composable\", () => {\n get('users', 0, 'name')(store).should.equal('Jack Sparrow')\n});\n\nit(\"extracts matching elements\", () => {\n get(matching(\"goldMember\"))(store.users).should.deep.equal([liz])\n})\n\nit(\"composes with traversals\", () => {\n get(\"users\", all, \"posts\")(store).should.deep.equal([jack.posts, liz.posts, bill.posts])\n})\n\nit(\"preserves structure with traversals\", () => {\n get(\"byName\", all, \"goldMember\")(store).should.deep.equal({jack: false, liz: true, bill: false})\n})\n\nit(\"nests traverals in output\", () => {\n get(\"users\", all, \"posts\", all, \"likes\")(store).should.deep.equal([[5, 70], [10000, 5000], [3000]])\n})\n\nit(\"handles folds as lenses\", () => {\n get(\"users\", 0, \"posts\", maxBy('likes'), 'likes')(store).should.equal(70)\n})\n\n```\n\n \n\n```typescript\nexpectType \n\n```javascript\nit('works', () => {\n add(5)(2).should.be.equal(7);\n [1, 2, 3].map(add(5)).should.deep.equal([6, 7, 8]);\n})\n\n```\n\n \n\n```typescript\nexpectType \n\n```javascript\nit('works', () => {\n sub(5)(2).should.be.equal(-3);\n [1, 2, 3].map(sub(5)).should.deep.equal([-4, -3, -2]);\n})\n\n```\n\n \n\n```typescript\nexpectType \n\n```javascript\nit('checks for inclusion', () => {\n includes('he')('hello').should.be.true\n includes('hello')('he').should.be.false\n})\n\n```\n\n \n\n```typescript\nexpectType \n\n```javascript\nit('checks for inclusion', () => {\n includesi('he')('hello').should.be.true\n includesi('hello')('he').should.be.false\n})\n\nit('ignores case', () => {\n includesi('HE')('hello').should.be.true\n includesi('He')('hEllo').should.be.true\n includesi('hello')('he').should.be.false\n})\n\n```\n\n \n\n```typescript\nexpectType \n\n```javascript\nit('should act as identity with get', () => {\n get(all)([1, 2, 3, 4]).should.deep.equal([1, 2, 3, 4]);\n get(all)({ a: 1, b: 2, c: 3, d: 4 }).should.deep.equal({ a: 1, b: 2, c: 3, d: 4 });\n});\n\nit('should allow multifoci gets', () => {\n get('a', all, 'b')({ a: [{ b: 1 }, { b: 2 }] }).should.deep.equal([ 1, 2 ]);\n});\n\nit('should allow deep multifoci gets', () => {\n const store = {\n users: [\n {\n blog: {\n posts: [\n {\n title: 'Hi'\n }\n ]\n }\n }\n ]\n };\n get('users', all, 'blog', 'posts', all, 'title')(store).should.deep.equal(\n [['Hi']]\n );\n});\n\nit('should allow deep multifoci mods', () => {\n const store = {\n users: [\n {\n blog: {\n posts: [\n {\n title: 'Hi'\n }\n ]\n }\n }\n ]\n };\n mod('users', all, 'blog', 'posts', all, 'title')(s => s.toLowerCase())(\n store\n ).users[0].blog.posts[0].title.should.equal('hi');\n});\n\nit('should act as map with mod', () => {\n assert.deepStrictEqual([2, 3, 4, 5], mod(all)(inc)([1, 2, 3, 4]));\n assert.deepStrictEqual(\n { a: 2, b: 3, c: 4, d: 5 },\n mod(all)(inc)({ a: 1, b: 2, c: 3, d: 4 })\n );\n});\n\n\nit('should compose in the middle of a lens and act as map', () => {\n assert.deepStrictEqual(\n [{ n: 1, c: 5 }, { n: 2, c: 7 }],\n mod(all, 'c')(inc)([{ n: 1, c: 4 }, { n: 2, c: 6 }])\n );\n});\n\nit('should compose in the middle of multiple lenses', () => {\n mod(all, 'c', all)(inc)([\n { n: 1, c: { d: 1, e: 7 } },\n { n: 2, c: { d: 1, e: 7 } }\n ]).should.deep.equal(\n [{ n: 1, c: { d: 2, e: 8 } }, { n: 2, c: { d: 2, e: 8 } }]\n );\n});\n\nit('should work in function form as well', () => {\n Object.entries(all).should.deep.equal(Object.entries(all()))\n});\n\n```\n\n \n\n```typescript\nexpectType \n\n```javascript\nit('acts as a reducer', () => {\n get('users', findBy({name: 'Jack Sparrow'}), 'name')(store).should.equal('Jack Sparrow')\n get('users', findBy('goldMember'), 'name')(store).should.equal('Elizabeth Swan')\n})\n\nit('uses of as an alias', () => {\n get('users', findBy.of({name: 'Jack Sparrow'}), 'name')(store).should.equal('Jack Sparrow')\n get('users', findBy.of('goldMember'), 'name')(store).should.equal('Elizabeth Swan')\n})\n\nit('produces undefined when it cant find something', () => {\n should.not.exist(get('users', findBy({name: 'frank'}))(store))\n})\n\n```\n\n \n\n```typescript\nexpectType \n\n```javascri","readmeFilename":"README.md"}TypeScript Usage
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