Support for Scala 3

[ryanstull]

No description provided.

[RileyDByrd]

Hi, Ryan. I wrote a flat implementation of Option using opaque types over type unions with Null for Scala 3. I think this could help you in writing support for Scala 3 for ScalaNullSafe.

Here's the implementation, https://github.com/RileyDByrd/option-replacement/blob/master/src/main/scala/FlatOptionModule.scala.

Here's the benchmark code, https://github.com/RileyDByrd/option-replacement-benchmark/tree/master/src/test/scala.

And here are the benchmarks. It performs as well as if-statements.

[info] # Run complete. Total time: 00:12:33
[info] REMEMBER: The numbers below are just data. To gain reusable insights, you need to follow up on
[info] why the numbers are the way they are. Use profilers (see -prof, -lprof), design factorial
[info] experiments, perform baseline and negative tests that provide experimental control, make sure
[info] the benchmarking environment is safe on JVM/OS/HW level, ask for reviews from the domain experts.
[info] Do not assume the numbers tell you what you want them to tell.
[info] NOTE: Current JVM experimentally supports Compiler Blackholes, and they are in use. Please exercise
[info] extra caution when trusting the results, look into the generated code to check the benchmark still
[info] works, and factor in a small probability of new VM bugs. Additionally, while comparisons between
[info] different JVMs are already problematic, the performance difference caused by different Blackhole
[info] modes can be very significant. Please make sure you use the consistent Blackhole mode for comparisons.
[info] Benchmark                            (size)  Mode  Cnt     Score    Error  Units
[info] FlatOptionBenchmarks.measureFlatMap       1  avgt   15     7.758 ┬▒  1.696  ns/op
[info] FlatOptionBenchmarks.measureFlatMap      10  avgt   15    13.654 ┬▒  0.182  ns/op
[info] FlatOptionBenchmarks.measureFlatMap     100  avgt   15    97.570 ┬▒ 16.698  ns/op
[info] FlatOptionBenchmarks.measureFlatMap    1000  avgt   15  1863.216 ┬▒  7.887  ns/op
[info] FlatOptionBenchmarks.measureMap           1  avgt   15     6.118 ┬▒  0.091  ns/op
[info] FlatOptionBenchmarks.measureMap          10  avgt   15    13.461 ┬▒  0.155  ns/op
[info] FlatOptionBenchmarks.measureMap         100  avgt   15    89.379 ┬▒  0.927  ns/op
[info] FlatOptionBenchmarks.measureMap        1000  avgt   15  1864.249 ┬▒ 16.321  ns/op
[info] IfThenElseBenchmarks.measureFlatMap       1  avgt   15     6.003 ┬▒  0.072  ns/op
[info] IfThenElseBenchmarks.measureFlatMap      10  avgt   15    13.251 ┬▒  0.084  ns/op
[info] IfThenElseBenchmarks.measureFlatMap     100  avgt   15    90.911 ┬▒  2.780  ns/op
[info] IfThenElseBenchmarks.measureFlatMap    1000  avgt   15  1849.186 ┬▒ 15.827  ns/op
[info] IfThenElseBenchmarks.measureMap           1  avgt   15     6.274 ┬▒  0.055  ns/op
[info] IfThenElseBenchmarks.measureMap          10  avgt   15    14.322 ┬▒  0.110  ns/op
[info] IfThenElseBenchmarks.measureMap         100  avgt   15    91.964 ┬▒  0.586  ns/op
[info] IfThenElseBenchmarks.measureMap        1000  avgt   15  2963.798 ┬▒ 26.699  ns/op
[info] OptionBenchmarks.measureFlatMap           1  avgt   15     7.216 ┬▒  0.249  ns/op
[info] OptionBenchmarks.measureFlatMap          10  avgt   15    27.343 ┬▒  0.192  ns/op
[info] OptionBenchmarks.measureFlatMap         100  avgt   15   218.185 ┬▒  1.505  ns/op
[info] OptionBenchmarks.measureFlatMap        1000  avgt   15  3714.361 ┬▒ 51.253  ns/op
[info] OptionBenchmarks.measureMap               1  avgt   15     7.883 ┬▒  0.062  ns/op
[info] OptionBenchmarks.measureMap              10  avgt   15    44.384 ┬▒  0.527  ns/op
[info] OptionBenchmarks.measureMap             100  avgt   15   406.676 ┬▒  2.955  ns/op
[info] OptionBenchmarks.measureMap            1000  avgt   15  4797.272 ┬▒ 41.573  ns/op

[ryanstull]

Hey @RileyDByrd , thanks for your interest in the project! I'm not sure if I'll be able to use these opaque type aliases for my Scala 3 implementation since I need to rewrite the ASTs in order to do what the macro does, but it is an interesting approach.

[RileyDByrd]

@ryanstull, no worries. I'll keep using this FlatOption implementation at least for now, but I eagerly await your Scala 3 implementation!