I can understand the business reasons behind it, but it would be much better if these checks were implemented directly in mainstream compilers for the benefit of everyone.
Ocaml has both structural and referential equality tests automatically. Unfortunately (for C-style programmers), structural equality uses "=", while referential equality uses "==".
From the Ocaml doc:
>On mutable types such as references, arrays, byte sequences, records with mutable fields and objects with mutable instance variables, e1 == e2 is true if and only if physical modification of e1 also affects e2. On non-mutable types, the behavior of ( == ) is implementation-dependent; however, it is guaranteed that e1 == e2 implies compare e1 e2 = 0.
Yep, and Ocaml equality is a giant pain. As for ==, referential equality is almost never what you want, so it’s (IMO) unwise to expose it except as an unsafe primitive. As for =, OCaml’s “polymorphic”/“structural” equality is usually wrong for any non-trivial data structure, so all the comparison-based standard library are functorized over comparison anyway. Use of polymorphic ‘=‘ is basically banned in the codebase I work on.
Haskell’s Eq/Ord typeclasses are vastly easier to use and harder to mess up. I think this particular use case is a more or less unambiguous win for typeclasses.