Crate type_equalities

Implements TypeEq that can be passed around and used at runtime to safely coerce values, references and other structures dependending on these types.

The equality type is zero-sized, and the coercion should optimize to a no-op in all cases.

Structs

ComposeF	Composition for TypeFunctions, i.e. ApF<ComposeF<F, G>, T> == ApF<F, ApF<G, T>>
IdF	The identity TypeFunction, ApF<IdF, T> == T. Coercing through this gives us the basic safe transmute.
LoefIdF	A TypeFunction version of the Martin-Löf identity type: ApF<LoefIdF<T>, U> == TypeEq<T, U>.
LoefIdFlippedF	LoefIdF flipped, i.e. ApF<LoefIdFlippedF<T>, U> == TypeEq<U, T>
MutRefF	The TypeFunction ApF<MutRefF<'a>, A> == &'a mut A
RefF	The TypeFunction ApF<RefF<'a>, A> == &'a A
SliceF	The TypeFunction ApF<SliceF<N>, A> == [A; N]
TypeEq	Evidence of the equality T == U as a zero-sized type.

Traits

AliasSelf	Trait used to convince the rust type checker of the claimed equality
Consumer	A consumer recives evidence of a type equality T == U and computes a result.
IsEqual	Equality at a constraint level, as a type alias. Reflexivity holds.
TypeFunction	A trait for type level functions, mapping type arguments to type results.

Functions

coerce	Coerce a value of type T to a value of type U, given evidence that T == U.
coerce_box	Coerce a value of type Box<T> to a value of type Box<U>, given evidence that T == U.
coerce_mut	Coerce a value of type &mut T to a value of type &mut U, given evidence that T == U.
coerce_ref	Coerce a value of type &T to a value of type &U, given evidence that T == U.
refl	Construct evidence of the reflexive equality T == T.
substitute	Our internal workhorse for most of the other coerce implementations, lifting the equality through an arbitrary TypeFunction. Do consider using this before writing a custom Consumer.
trivial_eq	Construct evidence of TypeEq<T, U> under the constraint T: IsEqual<U>.

Type Definitions

ApF	The result of applying the TypeFunction F to T.