On Monday, 19 April 2021 at 06:37:03 UTC, FeepingCreature wrote:
This is a social issue more than a technical one. The framework can help, by limiting access to disk and URLs and allowing tracing and hijacking, but ultimately you have to rely on code to not do crazy things.
I think the downsides are conceptual and technical, not social. If you can implement a version counter then you get all kinds of problems, like first compilation succeeding, then the second compilation failing with no code changes. Also, you can no longer cache intermediate representations between compilations without a rather significant additional machinery. It is better to do this in a more functional way, so you can generate a file, but it isn't written to disk, it is an abstract entity during compilation and is turned into something concrete after compilation.
to find out what works and what doesn't, and you can't gather experience with what people actually want to do and how it works in practice if you lock things down from the start. In
That's ok for a prototype, but not for a production language.
Most of my annoyances with D are issues where D isn't willing to take an additional step even though it would be technically very feasible. No implicit conversion for user-defined types, no arbitrary IO calls in CTFE, no returning AST trees from CTFE functions that are automatically inserted to create macros, and of course the cumbersome specialcased metaprogramming for type inspection instead of just letting us pass a type object to a ctfe function and calling methods on it.
So, anything that can be deduced from the input is fair game, but allowing arbitrary I/O is a completely different beast, compilation has to be idempotent. It should not be possible to write a program where the first compilation succeeds and the second compilation fails with no code changes between the compilation executions. Such failures should be limited to the build system so that you can quickly correct the problem.
IMHO, a good productive language makes debugging easier, faster and less frequently needed. Anything that goes against that is a move in the wrong direction.
