`@safe` by default. What about `@pure` and `immutable` by default?

Tue Apr 16 08:32:46 UTC 2019

On Tuesday, 16 April 2019 at 03:59:38 UTC, Mike Franklin wrote:
>
> Can anyone save me some trouble and articulate why it would be 
> bad to have `pure` and/or `immutable` by default?

Immutable by default may be ok for Haskell (I haven't tried), but 
sounds terrible for D, or most of the perfectly good programs 
anyone may have written or will write in the future in any 
language.