Misfortunate

Misfortunate is a collection of perverse implementations of safe Rust traits

Perverse?

Rust's safe traits come with some reasonable expectation for how they're intended to work. But unlike unsafe traits the language promises your program does not have Undefined Behaviour even if you don't obey.

Misfortunate provides implementations which conform to any function signatures for the trait, and so can indeed be used as implementations of that trait, yet they defy the expectations set out in the standard.

Example: Eq is a trait promising that this type exhibits equivalence, and Hash is a trait promising a type can be hashed in a consistent way. Misfortunate's Maxwell type implements both and yet every instance has an identical hash, while none of them are equal to each other or themselves.

C++

If you have extensive experience with C++ this might seem like a weird idea. Unlike Rust's traits, each C++ concept is defined only by its syntax. Any semantics are a matter for the programmer to consider. So for example in C++ float is std::totally_ordered and it is the responsibility of a programmer using an algorithm that requires std::totally_ordered types with floats to ensure they are never NaN. Whereas in Rust f32 is not Ord and so you won't mistakenly try to sort a Vec of NaNs.

As a result a collection of types like this one wouldn't make much sense in C++. In Rust however, types which do not in fact exhibit the desired characteristics will not generally implement a trait at all and the types presented here do so for your amusement and enlightenment.

Traits so far

std::cmp::Eq is implemented in Always, Echo, Everything, Funhouse, Jumble, Maxwell, Mirror, Nothing, Oneway{Equal, Greater, Less}, Reverse

std::cmp::Ord is implemented in Always, Echo, Jumble, Oneway{Equal, Greater, Less}, Reverse

std::hash::Hash is implemented in Maxwell

std::io::{Read, Write} are implemented in BlackHole, LoadLetter

std::fmt::Write is implemented in BlackHole, Pristine

std::borrow::{Borrow, BorrowMut} are implemented in Loaner

std::iter::ExactSizeIterator is implemented in Comte

std::clone::Clone is implemented in Multiplicity

std::iter::Extend is implemented in BlackHole

std::iter::FromIterator is implemented in BlackHole

std::iter::{Product, Sum} are implemented in Nice

std::ops::{Deref, DerefMut} are implemented in Double

std::str::FromStr is implemented in BlackHole

NB Some of the traits may necessarily also be implemented but in a more conventional way for structures they don't list

Ideas

A type with random Order behaviour, perhaps named Tombola ?