Lambda the Ultimate

Looking to write a language that combines primitive and object types with a prototypic approach ala Self, I am struggling to understand how to implement generic types. I read the GNAT Ada interface implementation document but did not see material directly related to this.

My concerns are:

• Adjust the size of the object to the parameterized type(s)
• Adjust the methods code to the parameterized type(s)
• Compare instantiated generic types for compatibility (eg. two instances of the type with covariant method parameters)

In particular, how do languages that support generic types handle the second point?