From e60cd10d06d1319fc7330bc56e367a249b5e0aaf Mon Sep 17 00:00:00 2001
From: Bernard Lambeau <blambeau@gmail.com>
Date: Thu, 9 Jun 2022 16:04:27 +0200
Subject: [PATCH] Add core.literal lens.

---
 CHANGELOG.md                       |  4 ++++
 README.md                          |  1 +
 lib/monolens/core.rb               |  6 ++++++
 lib/monolens/core/literal.rb       | 11 +++++++++++
 spec/monolens/core/test_literal.rb | 13 +++++++++++++
 5 files changed, 35 insertions(+)
 create mode 100644 lib/monolens/core/literal.rb
 create mode 100644 spec/monolens/core/test_literal.rb

diff --git a/CHANGELOG.md b/CHANGELOG.md
index ee276b1..7aeefec 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 0.5.3
+
+* Add core.literal lens.
+
 ## 0.5.2 - 2022-05-20
 
 * Add check.notEmpty lens that throw an error if the input is
diff --git a/README.md b/README.md
index 9dd0b78..0038730 100644
--- a/README.md
+++ b/README.md
@@ -79,6 +79,7 @@ result = lens.call(input)
 core.dig          - Extract from the input value (object or array) using a path.
 core.chain        - Applies a chain of lenses to an input value
 core.mapping      - Converts the input value via a key:value mapping
+core.literal      - Returns a constant value takens as lens definition
 
 str.strip         - Remove leading and trailing spaces of an input string
 str.split         - Splits the input string as an array
diff --git a/lib/monolens/core.rb b/lib/monolens/core.rb
index f124b83..be72558 100644
--- a/lib/monolens/core.rb
+++ b/lib/monolens/core.rb
@@ -10,6 +10,11 @@ def dig(options)
     end
     module_function :dig
 
+    def literal(options)
+      Literal.new(options)
+    end
+    module_function :literal
+
     def mapping(options)
       Mapping.new(options)
     end
@@ -21,3 +26,4 @@ def mapping(options)
 require_relative 'core/chain'
 require_relative 'core/dig'
 require_relative 'core/mapping'
+require_relative 'core/literal'
diff --git a/lib/monolens/core/literal.rb b/lib/monolens/core/literal.rb
new file mode 100644
index 0000000..778b589
--- /dev/null
+++ b/lib/monolens/core/literal.rb
@@ -0,0 +1,11 @@
+module Monolens
+  module Core
+    class Literal
+      include Lens
+
+      def call(arg, world = {})
+        option(:defn)
+      end
+    end
+  end
+end
diff --git a/spec/monolens/core/test_literal.rb b/spec/monolens/core/test_literal.rb
new file mode 100644
index 0000000..95db806
--- /dev/null
+++ b/spec/monolens/core/test_literal.rb
@@ -0,0 +1,13 @@
+require 'spec_helper'
+
+describe Monolens, "core.literal" do
+  let(:lens) do
+    Monolens.lens('core.literal' => { defn: 'hello' })
+  end
+
+  it 'works' do
+    input = {}
+    expected = 'hello'
+    expect(lens.call(input)).to eql(expected)
+  end
+end