scala-sandbox

Random Scala thought experiments and miscellany.

Modules

rankNClassy

Translation of "Rank 'n Classy Limited Effects from Haskell to Scala.

• Rank 'n Classy Limited Effects

taglessStackSafety

Explorations into making tagless final EDSLs stack safe.

• Alternatives to GADTs in Scala
• Tagless-Final Style

This project comes with a toy benchmark that can be run with:

$ sbt "taglessStackSafety/jmh:run -i 10 -wi 10 -f 2 -t 1 taglessStackSafety.ExprBenchmark"

Below are results from running on my local machine:

[info] Benchmark                                             Mode  Cnt  Score   Error  Units
[info] taglessStackSafety.ExprBenchmark.freeLoop            thrpt   20  5.387 ± 0.144  ops/s
[info] taglessStackSafety.ExprBenchmark.freeReduceLeft      thrpt   20  5.819 ± 0.116  ops/s
[info] taglessStackSafety.ExprBenchmark.freeReduceRight     thrpt   20  5.284 ± 0.159  ops/s
[info] taglessStackSafety.ExprBenchmark.taglessLoop         thrpt   20  5.131 ± 0.185  ops/s
[info] taglessStackSafety.ExprBenchmark.taglessReduceRight  thrpt   20  5.194 ± 0.245  ops/s

While writing these benchmarks I've realized how finicky stack safety can get. The benchmark for finally tagless only uses reduceRight - with reduceLeft it will blow the stack due to the evaluation differences of the two (non-strict vs. strict, respectively). Contrast with the Free algebra which does fine with both since stack safety is built in to the structure.

License

Code is provided under the Apache 2.0 license available at https://www.apache.org/licenses/LICENSE-2.0, as well as the LICENSE file.