DIP 1017--Add Bottom Type--Final Review
Tobias Müller
troplin at bluewin.ch
Wed Jan 16 06:40:22 UTC 2019
Johan Engelen <j at j.nl> wrote:
> Rust is indeed interesting here because, as far as I understand,
> Rust used to have a bottom type but they removed it because it
> was causing too much trouble. So we'd need to learn from them why
> `!` is not a bottom type proper in Rust, and what justification
> they have for `!` being a not-quite-bottom type and how that
> applies to D.
AFAIK the reason is, that Rust has no subtyping in the language. In type
theory, the bottom type is the subtype of all other types, which is
difficult to achieve without proper subtyping.
Tobi
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