Could you elaborate on the costs of the features mentioned about Haskell? As just one example, ADTs in Haskell are implemented in an extremely efficient fashio

Could you elaborate on the costs of the features mentioned about Haskell? As just one example, ADTs in Haskell are implemented in an extremely efficient fashion. Type classes are implemented in the same way that Go's interfaces are implemented (basically the same way as vtables are in C++). The immutability features (const) are compile-time checks, and can even help the compiler be more efficient. "if as an expression" has no real cost.