fix Just and Nothing toString methods to return value.

package.json

@@ -1,6 +1,6 @@
 {
   "name": "mojiscript",
-  "version": "0.8.1",
+  "version": "0.9.0",
   "description": "MojiScript is an Async First, opinionated, and functional language designed to have 100% compatibility with JavaScript engines.",
   "repository": {
     "type": "git",

type/Just.js

@@ -11,10 +11,6 @@ const Just = value => Object.create(
   }
 )
 
-function toString() {
-  return `Just (${JSON.stringify(this.value)})`
-}
-
 function map(func) {
   return Just(func(this.value))
 }
@@ -23,8 +19,8 @@ const prototype = {
   '@@type': typeJust,
   map,
   'fantasy-land/map': map,
-  toString,
-  inspect: toString,
+  toString() { return this.value.toString() },
+  inspect() { return `Just (${JSON.stringify(this.value)})` },
   toJSON() { return this.value }
 }
 

type/Nothing.js

@@ -3,7 +3,7 @@ const { typeNothing } = require('./_allTypes')
 const Nothing = Object.freeze(Object.create(
   {
     '@@type': typeNothing,
-    toString: () => 'Nothing',
+    toString: () => '',
     inspect: () => 'Nothing',
     map: () => Nothing,
     'fantasy-land/map': () => Nothing,

type/__tests__/Just.test.js

@@ -35,14 +35,14 @@ describe('type/Just', () => {
 
   test('Just(888).toString', () => {
     expect.assertions(1)
-    const expected = 'Just (888)'
+    const expected = '888'
     const actual = Just(888).toString()
     expect(actual).toBe(expected)
   })
 
   test('Just(abc).toString', () => {
     expect.assertions(1)
-    const expected = 'Just ("abc")'
+    const expected = 'abc'
     const actual = Just('abc').toString()
     expect(actual).toBe(expected)
   })
@@ -67,4 +67,25 @@ describe('type/Just', () => {
     const actual = Just(888)['@@type']
     expect(actual).toBe(expected)
   })
+
+  test('cast to string', () => {
+    expect.assertions(1)
+    const expected = 'a'
+    const actual = `${Just('a')}`
+    expect(actual).toBe(expected)
+  })
+
+  test('append strings', () => {
+    expect.assertions(1)
+    const expected = 'ab'
+    const actual = Just('a') + Just('b')
+    expect(actual).toBe(expected)
+  })
+
+  test('Number(Just()) returns number', () => {
+    expect.assertions(1)
+    const expected = 3
+    const actual = Number(Just(3))
+    expect(actual).toBe(expected)
+  })
 })

type/__tests__/Nothing.test.js

@@ -28,7 +28,7 @@ describe('type/Nothing', () => {
 
   test('toString', () => {
     expect.assertions(1)
-    const expected = 'Nothing'
+    const expected = ''
     const actual = Nothing.toString()
     expect(actual).toBe(expected)
   })
@@ -60,4 +60,11 @@ describe('type/Nothing', () => {
     const actual = Object.keys(Nothing)
     expect(actual).toEqual(expected)
   })
+
+  test('Number(Nothing) returns 0', () => {
+    expect.assertions(1)
+    const expected = 0
+    const actual = Number(Nothing)
+    expect(actual).toBe(expected)
+  })
 })