Merge pull request #2 from gcanti/optional

fix Optional.fromProp

package.json

@@ -1,6 +1,6 @@
 {
   "name": "monocle-ts",
-  "version": "0.0.3",
+  "version": "0.0.4",
   "description": "A porting of scala monocle library to TypeScript",
   "files": [
     "lib",

src/index.ts

@@ -141,9 +141,9 @@ export class Optional<S, A> {
   ){}
 
   /** generate an optional from a type and a prop */
-  static fromProp<T, P extends keyof T, V extends T[P]>(prop: P): Optional<T, V> {
-    return new Optional<T, V>(
-      s => s[prop] != null ? option.some(s[prop]) : option.none,
+  static fromProp<T extends { [K in P]: Option<any> }, P extends keyof T>(prop: P): Optional<T, T[P]> {
+    return new Optional<T, T[P]>(
+      s => s[prop],
       (a, s) => Object.assign({}, s, { [prop as any]: a })
     )
   }

test/Optional.ts

@@ -0,0 +1,22 @@
+import { Option, none, some } from 'fp-ts/lib/Option'
+import { Optional } from '../src'
+import { eqOptions as eq } from './helpers'
+
+type A = {
+  a: Option<number>
+}
+
+const optional = Optional.fromProp<A, 'a'>('a')
+
+describe('Optional', () => {
+
+  it('getOption', () => {
+    eq(optional.getOption({ a: none }), none)
+  })
+
+  it('set', () => {
+    eq(optional.set(none, { a: some(1) }).a, none)
+    eq(optional.set(some(2), { a: some(1) }).a, some(2))
+  })
+
+})

test/helpers.ts

@@ -0,0 +1,10 @@
+import * as assert from 'assert'
+import { HKTOption, isSome, isNone } from 'fp-ts/lib/Option'
+
+export function eqOptions<A>(x: HKTOption<A>, y: HKTOption<A>) {
+  if (isSome(x) && isSome(y)) {
+    assert.deepEqual(x.value, y.value)
+  } else {
+    assert.strictEqual(isNone(x), isNone(y))
+  }
+}

test/tsconfig.json

@@ -0,0 +1,16 @@
+{
+  "compilerOptions": {
+    "strictNullChecks": true,
+    "noImplicitAny": true,
+    "noImplicitReturns": true,
+    "noImplicitThis": true,
+    "noUnusedLocals": true,
+    "noUnusedParameters": true,
+    "noFallthroughCasesInSwitch": true,
+    "noEmit": true,
+    "forceConsistentCasingInFileNames": true,
+    "lib": [
+      "es6", "dom"
+    ]
+  }
+}