restructure project

internal/builtins/last.go

@@ -0,0 +1,25 @@
+package builtins
+
+import (
+	"monkey/internal/object"
+	"monkey/internal/typing"
+)
+
+// Last ...
+func Last(args ...object.Object) object.Object {
+	if err := typing.Check(
+		"last", args,
+		typing.ExactArgs(1),
+		typing.WithTypes(object.ARRAY_OBJ),
+	); err != nil {
+		return newError(err.Error())
+	}
+
+	arr := args[0].(*object.Array)
+	length := len(arr.Elements)
+	if length > 0 {
+		return arr.Elements[length-1]
+	}
+
+	return nil
+}