4 ms·

Is it too much to ask for null safety in the type system?

by arein3 3y ago

gavinray 3y ago
Nope not at all, here you go: https://openjdk.org/jeps/401 https://openjdk.org/jeps/401 It's part of Valhalla, as a pre-requirement for heap-flattening. Ctrl+F for "Null-restricted type". The strawman proposal syntax is "Foo!". When inlined, a null-restricted class type should have a heap storage footprint and execution time (when fully optimized) comparable to the primitive types. For example, a Point!, given the class declaration above, can be expected to directly occupy 128 bits in fields and array components, and to avoid any allocation in stack computations. A field access simply references the first or second 64 bits. There are no additional pointers. For a summary of current status and what it means for you as a developer, I recommend the linked email here and the author's comments in the thread: https://www.reddit.com/r/java/comments/13xtog3/valhallas_latest_plans_very_highlevel_accessible/ https://www.reddit.com/r/java/comments/13xtog3/valhallas_lat...
- arein3 3y ago
  Thanks, hopefully it will be live sooner rather than later.
ArturSkowronski 3y ago
In recent publication Brian Goetz explains why it is so complex to introduce one: https://mail.openjdk.org/pipermail/valhalla-spec-experts/2023-May/002276.html https://mail.openjdk.org/pipermail/valhalla-spec-experts/202... Great read. TLDR: It is hard to decide what the defaults should looks like, so they plan to add special markers (! and ?) to allow programmers to pass that detail to objects with "undefined nullability" (without ! or ?).
gcau 3y ago
As a typescript developer who had to make something in java, it's so bizarre and alien to me that anything anywhere might be null, and I have to manually check if things are null everywhere, and then play a guessing game when I get a NPE. It feels like the most unsafe, unsound thing ever.
- kaba0 3y ago
  You could add a few @Nullable annotations to your code where you might return null and be completely null-safe. Nullness is a so-called trivial property, so it can be statically analyised even in such a bolted on way.
erik_seaberg 3y ago
On launch day, we absolutely should expect to see that. But after the industry spent 28 years producing a corpus that may or may not round-trip nulls, well, “I don’t have a solution but I have a lot of respect for the problem.”

Is it too much to ask for null safety in the type system?

by arein3 3y ago

Is it too much to ask for null safety in the type system?

Nope not at all, here you go: https://openjdk.org/jeps/401 https://openjdk.org/jeps/401 It's part of Valhalla, as a pre-requirement for heap-flattening. Ctrl+F for "Null-restricted type". The strawman proposal syntax is "Foo!". When inlined, a null-restricted class type should have a heap storage footprint and execution time (when fully optimized) comparable to the primitive types. For example, a Point!, given the class declaration above, can be expected to directly occupy 128 bits in fields and array components, and to avoid any allocation in stack computations. A field access simply references the first or second 64 bits. There are no additional pointers. For a summary of current status and what it means for you as a developer, I recommend the linked email here and the author's comments in the thread: https://www.reddit.com/r/java/comments/13xtog3/valhallas_latest_plans_very_highlevel_accessible/ https://www.reddit.com/r/java/comments/13xtog3/valhallas_lat...

arein3 3y ago
Thanks, hopefully it will be live sooner rather than later.

ArturSkowronski 3y ago

In recent publication Brian Goetz explains why it is so complex to introduce one: https://mail.openjdk.org/pipermail/valhalla-spec-experts/2023-May/002276.html https://mail.openjdk.org/pipermail/valhalla-spec-experts/202... Great read. TLDR: It is hard to decide what the defaults should looks like, so they plan to add special markers (! and ?) to allow programmers to pass that detail to objects with "undefined nullability" (without ! or ?).

gcau 3y ago

As a typescript developer who had to make something in java, it's so bizarre and alien to me that anything anywhere might be null, and I have to manually check if things are null everywhere, and then play a guessing game when I get a NPE. It feels like the most unsafe, unsound thing ever.

kaba0 3y ago
You could add a few @Nullable annotations to your code where you might return null and be completely null-safe. Nullness is a so-called trivial property, so it can be statically analyised even in such a bolted on way.

erik_seaberg 3y ago

On launch day, we absolutely should expect to see that. But after the industry spent 28 years producing a corpus that may or may not round-trip nulls, well, “I don’t have a solution but I have a lot of respect for the problem.”