typescript(option): feat: added the 'orLazy' helper

Signed-off-by: prescientmoon <git@moonythm.dev>

typescript/option/package.json

@@ -30,6 +30,7 @@
         "@types/chai": "^4.2.7",
         "@types/mocha": "^5.2.7",
         "@types/node": "^12.12.21",
+        "@types/sinon": "^7.5.1",
         "@wessberg/rollup-plugin-ts": "^1.1.83",
         "chai": "^4.2.0",
         "mocha": "^6.2.2",
@@ -37,6 +38,7 @@
         "rollup": "^1.27.14",
         "rollup-plugin-terser": "^5.1.3",
         "semantic-release": "^15.14.0",
+        "sinon": "^8.0.1",
         "ts-node": "^8.5.4",
         "typescript": "^3.7.4",
         "utility-types": "^3.10.0"

typescript/option/pnpm-lock.yaml

@@ -7,6 +7,7 @@ devDependencies:
   '@types/chai': 4.2.7
   '@types/mocha': 5.2.7
   '@types/node': 12.12.21
+  '@types/sinon': 7.5.1
   '@wessberg/rollup-plugin-ts': 1.1.83_rollup@1.27.14+typescript@3.7.4
   chai: 4.2.0
   mocha: 6.2.2
@@ -14,6 +15,7 @@ devDependencies:
   rollup: 1.27.14
   rollup-plugin-terser: 5.1.3_rollup@1.27.14
   semantic-release: 15.14.0_semantic-release@15.14.0
+  sinon: 8.0.1
   ts-node: 8.5.4_typescript@3.7.4
   typescript: 3.7.4
   utility-types: 3.10.0
@@ -959,6 +961,31 @@ packages:
       semantic-release: '>=15.8.0 <16.0.0 || >=16.0.0-beta <17.0.0'
     resolution:
       integrity: sha512-LGjgPBGjjmjap/76O0Md3wc04Y7IlLnzZceLsAkcYRwGQdRPTTFUJKqDQTuieWTs7zfHzQoZqsqPfFxEN+g2+Q==
+  /@sinonjs/commons/1.7.0:
+    dependencies:
+      type-detect: 4.0.8
+    dev: true
+    resolution:
+      integrity: sha512-qbk9AP+cZUsKdW1GJsBpxPKFmCJ0T8swwzVje3qFd+AkQb74Q/tiuzrdfFg8AD2g5HH/XbE/I8Uc1KYHVYWfhg==
+  /@sinonjs/formatio/4.0.1:
+    dependencies:
+      '@sinonjs/commons': 1.7.0
+      '@sinonjs/samsam': 4.2.0
+    dev: true
+    resolution:
+      integrity: sha512-asIdlLFrla/WZybhm0C8eEzaDNNrzymiTqHMeJl6zPW2881l3uuVRpm0QlRQEjqYWv6CcKMGYME3LbrLJsORBw==
+  /@sinonjs/samsam/4.2.0:
+    dependencies:
+      '@sinonjs/commons': 1.7.0
+      array-from: 2.1.1
+      lodash.get: 4.4.2
+    dev: true
+    resolution:
+      integrity: sha512-yG7QbUz38ZPIegfuSMEcbOo0kkLGmPa8a0Qlz4dk7+cXYALDScWjIZzAm/u2+Frh+bcdZF6wZJZwwuJjY0WAjA==
+  /@sinonjs/text-encoding/0.7.1:
+    dev: true
+    resolution:
+      integrity: sha512-+iTbntw2IZPb/anVDbypzfQa+ay64MW0Zo8aJ8gZPWMMK6/OubMVb6lUPMagqjOPnmtauXnFCACVl3O7ogjeqQ==
   /@thi.ng/api/6.6.0:
     dev: false
     resolution:
@@ -1046,6 +1073,10 @@ packages:
     dev: true
     resolution:
       integrity: sha512-1OzrNb4RuAzIT7wHSsgZRlMBlNsJl+do6UblR7JMW4oB7bbR+uBEYtUh7gEc/jM84GGilh68lSOokyM/zNUlBA==
+  /@types/sinon/7.5.1:
+    dev: true
+    resolution:
+      integrity: sha512-EZQUP3hSZQyTQRfiLqelC9NMWd1kqLcmQE0dMiklxBkgi84T+cHOhnKpgk4NnOWpGX863yE6+IaGnOXUNFqDnQ==
   /@types/ua-parser-js/0.7.33:
     dev: true
     resolution:
@@ -1214,6 +1245,10 @@ packages:
       node: '>=0.10.0'
     resolution:
       integrity: sha1-3wEKoSh+Fku9pvlyOwqWoexBh6E=
+  /array-from/2.1.1:
+    dev: true
+    resolution:
+      integrity: sha1-z+nYwmYoudxa7MYqn12PHzUsEZU=
   /array-ify/1.0.0:
     dev: true
     resolution:
@@ -2019,6 +2054,12 @@ packages:
       node: '>=4'
     resolution:
       integrity: sha1-tdRU3CGZriJWmfNGfloH87lVuv0=
+  /has-flag/4.0.0:
+    dev: true
+    engines:
+      node: '>=8'
+    resolution:
+      integrity: sha512-EykJT/Q1KjTWctppgIAgfSO0tKVuZUjhgMr17kqTumMl6Afv3EISleU7qZUzoXDFTAHTDC4NOoG/ZxU3EvlMPQ==
   /has-symbols/1.0.1:
     dev: true
     engines:
@@ -2263,6 +2304,10 @@ packages:
       node: '>=0.10.0'
     resolution:
       integrity: sha1-Thqg+1G/vLPpJogAE5cgLBd1tm4=
+  /isarray/0.0.1:
+    dev: true
+    resolution:
+      integrity: sha1-ihis/Kmo9Bd+Cav8YDiTmwXR7t8=
   /isarray/1.0.0:
     dev: true
     resolution:
@@ -2363,6 +2408,10 @@ packages:
       '0': node >= 0.2.0
     resolution:
       integrity: sha1-P02uSpH6wxX3EGL4UhzCOfE2YoA=
+  /just-extend/4.0.2:
+    dev: true
+    resolution:
+      integrity: sha512-FrLwOgm+iXrPV+5zDU6Jqu4gCRXbWEQg2O3SKONsWE4w7AXFRkryS53bpWdaL9cNol+AmR3AEYz6kn+o0fCPnw==
   /lines-and-columns/1.1.6:
     dev: true
     resolution:
@@ -2456,6 +2505,12 @@ packages:
       node: '>=4'
     resolution:
       integrity: sha512-VeIAFslyIerEJLXHziedo2basKbMKtTw3vfn5IzG0XTjhAVEJyNHnL2p7vc+wBDSdQuUpNw3M2u6xb9QsAY5Eg==
+  /lolex/5.1.2:
+    dependencies:
+      '@sinonjs/commons': 1.7.0
+    dev: true
+    resolution:
+      integrity: sha512-h4hmjAvHTmd+25JSwrtTIuwbKdwg5NzZVRMLn9saij4SZaepCrTCxPr35H/3bjwfMJtN+t3CX8672UIkglz28A==
   /loose-envify/1.4.0:
     dependencies:
       js-tokens: 4.0.0
@@ -2678,6 +2733,17 @@ packages:
     dev: true
     resolution:
       integrity: sha512-1nh45deeb5olNY7eX82BkPO7SSxR5SSYJiPTrTdFUVYwAl8CKMA5N9PjTYkHiRjisVcxcQ1HXdLhx2qxxJzLNQ==
+  /nise/3.0.0:
+    dependencies:
+      '@sinonjs/commons': 1.7.0
+      '@sinonjs/formatio': 4.0.1
+      '@sinonjs/text-encoding': 0.7.1
+      just-extend: 4.0.2
+      lolex: 5.1.2
+      path-to-regexp: 1.8.0
+    dev: true
+    resolution:
+      integrity: sha512-EObFx5tioBMePHpU/gGczaY2YDqL255iwjmZwswu2CiwEW8xIGrr3E2xij+efIppS1nLQo9NyXSIUySGHUOhHQ==
   /node-emoji/1.10.0:
     dependencies:
       lodash.toarray: 4.4.0
@@ -3094,6 +3160,12 @@ packages:
     dev: true
     resolution:
       integrity: sha512-GSmOT2EbHrINBf9SR7CDELwlJ8AENk3Qn7OikK4nFYAu3Ote2+JYNVvkpAEQm3/TLNEJFD/xZJjzyxg3KBWOzw==
+  /path-to-regexp/1.8.0:
+    dependencies:
+      isarray: 0.0.1
+    dev: true
+    resolution:
+      integrity: sha512-n43JRhlUKUAlibEJhPeir1ncUID16QnEjNpwzNdO3Lm4ywrBpBZ5oLD0I6br9evr1Y9JTqwRtAh7JLoOzAQdVA==
   /path-type/3.0.0:
     dependencies:
       pify: 3.0.0
@@ -3500,6 +3572,18 @@ packages:
       node: '>=6'
     resolution:
       integrity: sha512-iuh+gPf28RkltuJC7W5MRi6XAjTDCAPC/prJUpQoG4vIP3MJZ+GTydVnodXA7pwvTKb2cA0m9OFZW/cdWy/I/w==
+  /sinon/8.0.1:
+    dependencies:
+      '@sinonjs/commons': 1.7.0
+      '@sinonjs/formatio': 4.0.1
+      '@sinonjs/samsam': 4.2.0
+      diff: 4.0.1
+      lolex: 5.1.2
+      nise: 3.0.0
+      supports-color: 7.1.0
+    dev: true
+    resolution:
+      integrity: sha512-vbXMHBszVioyPsuRDLEiPEgvkZnbjfdCFvLYV4jONNJqZNLWTwZ/gYSNh3SuiT1w9MRXUz+S7aX0B4Ar2XI8iw==
   /slash/3.0.0:
     dev: true
     engines:
@@ -3721,6 +3805,14 @@ packages:
       node: '>=6'
     resolution:
       integrity: sha512-qe1jfm1Mg7Nq/NSh6XE24gPXROEVsWHxC1LIx//XNlD9iw7YZQGjZNjYN7xGaEG6iKdA8EtNFW6R0gjnVXp+wQ==
+  /supports-color/7.1.0:
+    dependencies:
+      has-flag: 4.0.0
+    dev: true
+    engines:
+      node: '>=8'
+    resolution:
+      integrity: sha512-oRSIpR8pxT1Wr2FquTNnGet79b3BWljqOuoW/h4oBhxJ/HUbX5nX6JSruTkvXDCFMwDPvsaTTbvMLKZWSy0R5g==
   /supports-hyperlinks/1.0.1:
     dependencies:
       has-flag: 2.0.0
@@ -4103,6 +4195,7 @@ specifiers:
   '@types/chai': ^4.2.7
   '@types/mocha': ^5.2.7
   '@types/node': ^12.12.21
+  '@types/sinon': ^7.5.1
   '@wessberg/rollup-plugin-ts': ^1.1.83
   chai: ^4.2.0
   mocha: ^6.2.2
@@ -4110,6 +4203,7 @@ specifiers:
   rollup: ^1.27.14
   rollup-plugin-terser: ^5.1.3
   semantic-release: ^15.14.0
+  sinon: ^8.0.1
   ts-node: ^8.5.4
   tslib: ^1.10.0
   typescript: ^3.7.4

typescript/option/src/helpers/external.ts

@@ -18,6 +18,7 @@ export * from './map'
 export * from './mapAsync'
 export * from './optionify'
 export * from './or'
+export * from './orLazy'
 export * from './toArray'
 export * from './toNullable'
 export * from './withDefault'

typescript/option/src/helpers/orLazy.test.ts

@@ -0,0 +1,48 @@
+import { expect } from 'chai'
+import { constantly } from '@thi.ng/compose'
+import { orLazy } from './orLazy'
+import { someX } from '../../test/constants'
+import { None } from '../types'
+import { spy } from 'sinon'
+
+describe('The orLazy helper', () => {
+    it("should return the first argument if it's Some", () => {
+        // act
+        const result = orLazy(someX, constantly(None))
+
+        // asser
+        expect(result).to.equal(someX)
+    })
+
+    it('should return the return of the second argument if the first is None', () => {
+        // act
+        const orSome = orLazy(None, constantly(someX))
+        const orNone = orLazy(None, constantly(None))
+
+        // assert
+        expect(orSome).to.equal(someX)
+        expect(orNone).to.equal(None)
+    })
+
+    it('should not evaluate the second argument if the first one is Some', () => {
+        // arrange
+        const func = spy(constantly(someX))
+
+        // act
+        orLazy(someX, func)
+
+        // assert
+        expect(func.called).to.be.false
+    })
+
+    it('should evaluate the second argument if the first one is None', () => {
+        // arrange
+        const func = spy(constantly(someX))
+
+        // act
+        orLazy(None, func)
+
+        // assert
+        expect(func.called).to.be.true
+    })
+})

typescript/option/src/helpers/orLazy.ts

@@ -0,0 +1,17 @@
+import { isSome } from './isSome'
+import { Option } from '../types'
+
+/**
+ * Lazy version of or.
+ * The second argument will only be evaluated if the first argument is Nothing.
+ *
+ * @param a The first argument.
+ * @param b The second argument.
+ */
+export const orLazy = <T>(a: Option<T>, b: () => Option<T>) => {
+    if (isSome(a)) {
+        return a
+    }
+
+    return b()
+}