Evaluate numbers

lib/chervil.rb

 require 'chervil/ast'
+require 'chervil/interpreter'
 require 'chervil/lexer'
 require 'chervil/parser'
 require 'chervil/token'

lib/chervil/ast/number.rb

       @value = value
     end
 
+    def evaluate
+      @value
+    end
+
     def ==(other)
       @value == other.value
     end

lib/chervil/interpreter.rb

+module Chervil
+  class Interpreter
+    def initialize(tree)
+      @tree = tree
+    end
+
+    def interpret
+      @tree.map(&:evaluate)
+    end
+  end
+end

spec/ast/number_spec.rb

+module Chervil::AST
+  RSpec.describe Number do
+    it 'evaluates' do
+      expect(Number.new(5.0).evaluate).to eq(5.0)
+    end
+  end
+end