fix(maybe): returns NonNullable root type (#31)

Author: patrickmichalina

package-lock.json

@@ -30,17 +30,17 @@
     "pkgRoot": "dist"
   },
   "devDependencies": {
-    "@types/jest": "^23.3.3",
-    "@types/node": "^10.11.4",
+    "@types/jest": "^23.3.4",
+    "@types/node": "^10.11.5",
     "codecov": "^3.1.0",
     "jest": "23.6.0",
     "jest-junit": "^5.2.0",
-    "rollup": "^0.66.4",
+    "rollup": "^0.66.5",
     "semantic-release": "^15.9.17",
     "ts-jest": "23.10.4",
     "ts-node": "^7.0.1",
     "tslint": "^5.11.0",
-    "tslint-immutable": "^4.7.0",
+    "tslint-immutable": "^4.8.0",
     "typescript": "^3.1.1",
     "uglify-js": "^3.4.9"
   },

package.json

@@ -22,12 +22,12 @@ export interface IMaybe<T> extends IMonad<T> {
   /**
    * Unwrap a Maybe with a default value
    */
-  valueOr(val: NonNullable<T>): NonNullable<T>
+  valueOr(val: NonNullable<T>): T
 
   /**
    * Unwrap a Maybe with a default computed value
    */
-  valueOrCompute(f: () => NonNullable<T>): NonNullable<T>
+  valueOrCompute(f: () => NonNullable<T>): T
 
   /**
    * Execute functions with side-effects.
@@ -42,7 +42,7 @@ export interface IMaybe<T> extends IMonad<T> {
   /**
    * Execute a function with side-effects when maybe is a some.
    */
-  tapSome(f: (val: NonNullable<T>) => void): void
+  tapSome(f: (val: T) => void): void
 
   /**
    * Unwrap and apply MaybePattern functions
@@ -52,12 +52,12 @@ export interface IMaybe<T> extends IMonad<T> {
   /**
    * Combine multiple maybe
    */
-  map<R>(f: (t: NonNullable<T>) => R): IMaybe<R>
+  map<R>(f: (t: T) => R): IMaybe<R>
 
   /**
    * Combine multiple maybe
    */
-  flatMap<R>(f: (t: NonNullable<T>) => IMaybe<R>): IMaybe<R>
+  flatMap<R>(f: (t: T) => IMaybe<R>): IMaybe<R>
 
   // tslint:disable-next-line:readonly-array
   of(x?: T, ...args: any[]): IMaybe<T>

src/interfaces/maybe.interface.ts

@@ -1,8 +1,8 @@
 import { IMaybe, IMaybePattern } from "../interfaces"
 
-export function maybe<T>(value?: T): IMaybe<T> {
+export function maybe<T>(value?: T): IMaybe<NonNullable<T>> {
   return {
-    of: (x) => maybe(x),
+    of: maybe,
     valueOr: (val: NonNullable<T>) => value === null || value === undefined ? val : value as NonNullable<T>,
     valueOrCompute: (f: () => NonNullable<T>) => value === null || value === undefined ? f() : value as NonNullable<T>,
     tap: (obj: Partial<IMaybePattern<T, void>>) => value === null || value === undefined ? obj.none && obj.none() : obj.some && obj.some(value as  NonNullable<T>),
@@ -12,4 +12,4 @@ export function maybe<T>(value?: T): IMaybe<T> {
     map: <R>(f: (t: NonNullable<T>) => R) => value === null || value === undefined ? maybe<R>() : maybe<R>(f(value as NonNullable<T>)),
     flatMap: <R>(f: (d:  NonNullable<T>) => IMaybe<R>) => value === null || value === undefined ? maybe<R>() : f(value as  NonNullable<T>)
   }
-}
+}