Evaluate addition

lib/chervil/ast/application.rb

     def ==(other)
       @expr == other.expr && @arguments == other.arguments
     end
+
+    def evaluate(env)
+      if @expr.class == Identifier
+        function = env.get(@expr.name)
+        function.call(@arguments.map { |arg| arg.evaluate(env) })
+      end
+    end
   end
 end

lib/chervil/core.rb

 module Chervil
   module Core
     CORE = {
-      "+" => Proc.new { |*args| args.inject(:+) },
-      "-" => Proc.new { |*args| args.inject(:-) },
-      "*" => Proc.new { |*args| args.inject(:*) },
-      "/" => Proc.new { |*args| args.inject(:/) },
+      "+" => Proc.new { |args| args.inject(:+) },
+      "-" => Proc.new { |args| args.inject(:-) },
+      "*" => Proc.new { |args| args.inject(:*) },
+      "/" => Proc.new { |args| args.inject(:/) },
     }
   end
 end

spec/ast/application_spec.rb

+module Chervil
+  RSpec.describe AST::Definition do
+    it 'evaluates addition' do
+      env = Env.new
+      expect(
+        AST::Application.new(
+          AST::Identifier.new('+'),
+          [AST::Number.new(1.0), AST::Number.new(2.0)]
+        )
+          .evaluate(env)
+      ).to eq(3.0)
+    end
+  end
+end

spec/env_spec.rb

   RSpec.describe Env do
     it 'has arithmetic from core' do
       env = Env.new
-      expect(env.get("+").call(1, 2)).to eq(3)
+      expect(env.get("+").call([1, 2])).to eq(3)
     end
 
     it 'inherits from parent env' do