Implements binding and evaluating function declarations

tests/integration/Functions.cpp

@@ -0,0 +1,17 @@
+#ifdef TESTS_BUILD
+#include <catch.hpp>
+#include "../src/Script.hpp"
+
+TEST_CASE( "Define script function", "[integration]" ) {
+    Script* script = Script::Create("function add(number a, number b) a + b end");
+    REQUIRE(!script->Diagnostics -> HasErrors());
+    script->Evaluate();
+    auto variable = script->GetVariable("add");
+    REQUIRE(variable != nullptr);
+    REQUIRE(variable->GetType()->GetClass() == TypeClass::Function);
+    delete script;
+}
+
+
+
+#endif