Function ghosts::materialize

pub fn materialize<T>(_: Ghost<T>) -> T

Ghost operation: extract an imaginary T value out of a Ghost<T> token.

THIS MUST ONLY BE USED FROM WITHIN A ghost! BLOCK

Or somewhere transitively called by a ghost! block exclusively.

Otherwise this call would try to make it to codegen, which it cannot do.

• the current implementation uses a polymorphization limitation to prevent this, which works, but is not detected by cargo check.

Non-error-prone replacements

• When directly inside a ghost! block, use materialize!.

• Otherwise, require that the caller pass some Ectoplasm, which they can have by materialize()-ing their own Ghost<Ectoplasm>.

  With it, you’ll have access to its impossible to misuse .materialize() method.

• Or perhaps way more simply, consider using the .map() or .and_then() adapters.