A computerized method is provided to consume a dynamically-typed language in a compatible language, and to compile source code in the compatible language to a target language. The methods make it possible to add type safety and static type checking to a superset of dynamically-typed languages, irrespective of whether the dynamically-typed languages are dynamically type-checked or not. In preferred embodiments, the methods allow for all types in an external language to be represented as a single type. In various embodiments, more than one unified external type can be allowed, each unified external type being specific to a group or class of types. In the methods, conversions are used as a mechanism to convert types. Conversions can be either implicit or explicit, and explicit conversions can be either implementation-defined or user-defined.