feat: Added additional Boolean, Union and Nilable types

fixes #6

Author: joelmoss

.rubocop.yml

@@ -7,6 +7,14 @@ Style/Documentation:
   Enabled: false
 Style/HashAsLastArrayItem:
   Enabled: false
+Style/CaseEquality:
+  Enabled: false
+Style/NilComparison:
+  Enabled: false
+
+Naming/MethodName:
+  Exclude:
+    - "lib/delivered/types.rb"
 
 Layout/LineLength:
   Max: 100
@@ -23,7 +31,6 @@ Metrics/CyclomaticComplexity:
   Enabled: false
 Metrics/PerceivedComplexity:
   Enabled: false
-
 Metrics/BlockLength:
   Exclude:
     - "test/**/*"

README.md

@@ -44,3 +44,57 @@ def create(name, age:)
   "User #{name} created with age #{age}"
 end
 ```
+
+### Delivered Types
+
+As well as Ruby's native types (ie. `String`, `Integer`, etc.), _Delivered_ provides a couple of
+extra types in `Delivered::Types`.
+
+You can call these directly with `Delivered::Types.Boolean`, or for brevity, assign
+`Delivered::Types` to `T` in your classes:
+
+```ruby
+class User
+  extend Delivered::Signature
+  T = Delivered::Types
+end
+```
+
+The following examples all use the `T` alias, and assumes the above.
+
+#### `Boolean`
+
+Value **MUST** be `true` or `false`. Does not support "truthy" or "falsy" values.
+
+```ruby
+sig validate: T.Boolean
+def create(validate:); end
+```
+
+#### `Union`
+
+Value **MUST** be a union of the given list of values, that is, the value must be one of the given list.
+
+```ruby
+sig T.Union(:male, :female)
+def create(gender); end
+```
+
+#### `Nilable`
+
+When a type is given, the value **MUST** be nil or of the given type.
+
+```ruby
+sig save: T.Nilable(String)
+def create(save: nil); end
+
+sig T.Nilable(String)
+def update(name = nil); end
+```
+
+If no type is given, the value **CAN** be nil. This essentially allows any value, including nil.
+
+```ruby
+sig save: T.Nilable
+def create(save: nil); end
+```

lib/delivered.rb

@@ -2,4 +2,5 @@
 
 module Delivered
   autoload :Signature, 'delivered/signature'
+  autoload :Types, 'delivered/types'
 end

lib/delivered/signature.rb

@@ -2,8 +2,6 @@
 
 module Delivered
   module Signature
-    NULL = Object.new
-
     def sig(*sig_args, **sig_kwargs, &return_blk)
       # ap [sig_args, sig_kwargs, return_blk]
 

lib/delivered/types.rb

@@ -0,0 +1,41 @@
+# frozen_string_literal: true
+
+module Delivered
+  class UnionType
+    def initialize(*types)
+      @types = types
+    end
+
+    def ===(value)
+      @types.any? { |type| type === value }
+    end
+  end
+
+  class NilableType
+    def initialize(type = nil)
+      @type = type
+    end
+
+    def ===(value)
+      (@type.nil? ? true : nil === value) || @type === value
+    end
+  end
+
+  class BooleanType
+    def initialize
+      freeze
+    end
+
+    def ===(value)
+      [true, false].include?(value)
+    end
+  end
+
+  module Types
+    module_function
+
+    def Nilable(type = nil) = NilableType.new(type)
+    def Union(*types) = UnionType.new(*types)
+    def Boolean = BooleanType.new
+  end
+end

test/delivered/signature.rb

@@ -35,6 +35,9 @@ def to_s = "#{@name}, #{@age}"
     sig { Integer }
     def age = @age.to_s
 
+    sig(Delivered::Types.Boolean)
+    def active=(val); end
+
     sig(String, _age: Integer) { Array }
     def self.where(_name, _age: nil) = []
 
@@ -106,6 +109,11 @@ def self.find_by_name(name) = User.new(name)
     end
   end
 
+  it 'raises on incorrect Delivered type' do
+    user = User.new('Joel')
+    expect { user.active = 1 }.to raise_exception NoMatchingPatternError
+  end
+
   it 'raises on missing args' do
     expect { User.new }.to raise_exception NoMatchingPatternError
   end

test/delivered/types.rb

@@ -0,0 +1,47 @@
+# frozen_string_literal: true
+
+describe Delivered::Types do
+  T = Delivered::Types
+
+  describe 'Union' do
+    it 'is within union' do
+      assert T.Union(:one, :two) === :one
+    end
+
+    it 'raises when value is not in union' do
+      expect { :three => ^(T.Union(:one, :two)) }.to raise_exception NoMatchingPatternError
+      expect { :one => ^(T.Union(:one, :two)) }.not.to raise_exception
+    end
+  end
+
+  describe 'Boolean' do
+    it 'should be true or false' do
+      assert T.Boolean === true
+      assert T.Boolean === false
+    end
+
+    it 'raises when not boolean' do
+      expect { 0 => ^(T.Boolean) }.to raise_exception NoMatchingPatternError
+    end
+  end
+
+  describe 'Nilable' do
+    it 'can be nil' do
+      assert T.Nilable === nil
+    end
+
+    with 'no given type' do
+      it 'can be any type' do
+        assert T.Nilable === 'hello'
+        expect { 'hello' => ^(T.Nilable) }.not.to raise_exception NoMatchingPatternError
+      end
+    end
+
+    it 'can receive another type' do
+      assert T.Nilable(String) === 'hello'
+      assert T.Nilable(String) === nil
+      expect { 'hello' => ^(T.Nilable(String)) }.not.to raise_exception
+      expect { 1 => ^(T.Nilable(String)) }.to raise_exception NoMatchingPatternError
+    end
+  end
+end