typescript(option): feat: added an optionify helper

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

typescript/option/src/helpers/external.ts

@@ -15,6 +15,7 @@ export * from './isSome'
 export * from './iter'
 export * from './map'
 export * from './mapAsync'
+export * from './optionify'
 export * from './toArray'
 export * from './toNullable'
 export * from './withDefault'

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

@@ -0,0 +1,17 @@
+import { expect } from 'chai'
+import { optionify } from './optionify'
+import { fromNullable } from './fromNullable'
+
+describe('The optionify helper', () => {
+    it('should create a function which returns an option instead of a nullable', () => {
+        // arrange
+        const func = (a: number, b: number) => (a > b ? a + b : null)
+
+        // act
+        const result = optionify(func)
+
+        // assert
+        expect(result(1, 2)).to.equal(fromNullable(func(1, 2)))
+        expect(result(2, 1)).to.equal(fromNullable(func(2, 1)))
+    })
+})

typescript/option/src/helpers/optionify.ts

@@ -0,0 +1,15 @@
+import { fromNullable } from './fromNullable'
+
+/**
+ * Takes a function which returns a nullable and creates
+ * a function which returns an Option.
+ * In functional programming this would be the same as
+ * composing the function with fromNullable.
+ *
+ * @param f The function to optionify
+ */
+export const optionify = <T extends unknown[], U>(
+    f: (...args: T) => U | null
+) => {
+    return (...args: T) => fromNullable(f(...args))
+}