Skip to content

Remove mention of "existentially-quantified types" from impl Trait chapter #73

@varkor

Description

@varkor

The More details section for impl Trait describes the type theoretic meaning of impl Trait in terms of existential types.

type parameters and impl Trait in argument position are universals (universally quantified types). Meanwhile, impl Trait in return position are existentials (existentially quantified types).

This is not quite right: argument-position impl Trait is also existentially-quantified, but is isomorphic to another universally-quantified type (as described here).

At the very least this explanation should be modified. Better still, all mention of existentially-quantified types could be removed entirely, as explaining impl Trait in terms of existential types has time and time again proven to cause more confusion than it resolves. The intuitive explanations earlier do a better job of describing impl Trait.

Metadata

Metadata

Assignees

No one assigned

    Labels

    No labels
    No labels

    Type

    No type

    Projects

    No projects

    Relationships

    None yet

    Development

    No branches or pull requests

    Issue actions