Re:Algebraic Data Types
by scott_s on Thursday July 31, 2014 @11:52AM
(#8114823)
Yes. I was thinking there was an important distinction about knowing the types statically, and being able to make sure that all options have been handled. But, if in the interface you say "everyone must implement this method" (as I did), and then you don't, the compiler will issue an error in much the same way.
What I was getting at is that when we use the algebraic version of AST, we know exhaustively what forms it can take. The definition tells us. In the OO version, this is note true. If we restrict our use to the polymorphic functions, then this is fine. But if we try to inspect the OO version of AST, ask its true type, and then act on it, then we may get into trouble.
What I was getting at is that when we use the algebraic version of AST, we know exhaustively what forms it can take. The definition tells us. In the OO version, this is note true. If we restrict our use to the polymorphic functions, then this is fine. But if we try to inspect the OO version of AST, ask its true type, and then act on it, then we may get into trouble.