[Haskell-cafe] Class invariants/laws

[Simon Peyton-Jones]

| > These invariants are basically impossible to enforce by the compiler,
| > but nonetheless certain classes have laws which are expected to hold,
| > and I would not be surprised if (for example) GHC optimization RULES
| > depended on them.
|
| I, in fact, would be surprised if there were such dependencies. (Not
| that there might not be good reasons to want to rely on such laws for
| some conceivable optimization, I just doubt that any implementation
| actually does.)
|
| Simon?

I don't believe GHC relies on any class laws.  It'd be pretty dangerous to do so, I think.

Simon