I was just trying to use `Path/of` in the past few days and it took awhile to get familiar with the Clojure varargs interop, so it's nice to see that pile has simple support for it already.

I was also wondering how much the use of more contemporary Java features could enhance the source code or the runtime performance. This implementation seems like a great test-bed for answering such questions.

A small aside: The README uses `Paths/get`, which might be deprecated eventually: https://github.com/openjdk/jdk/blob/b16e5584abcae18fdcc4494f...

Should just use `Path/of` directly.

BTW, I thought I would give it a try, but my initial naive attempt hasn't yielded any results:

     nix shell nixpkgs#maven nixpkgs#jdk20
    Restored session: Wed Sep 20 03:51:47 HKT 2023

    pile on  master is  v0.0.1-SNAPSHOT via  on   (ap-southeast-1) 
     java --version
    openjdk 20.0.2 2023-07-18
    OpenJDK Runtime Environment Zulu20.32+11-CA (build 20.0.2+9)
    OpenJDK 64-Bit Server VM Zulu20.32+11-CA (build 20.0.2+9, mixed mode, sharing)

    pile on  master is  v0.0.1-SNAPSHOT via  v20.0.2 on   (ap-southeast-1) 
     time ./repl             
    [INFO] Scanning for projects...
    [INFO] 
    [INFO] -------------------------< com.pile:pile-lang >-------------------------
    [INFO] Building pile-lang 0.0.1-SNAPSHOT
    [INFO]   from pom.xml
    [INFO] --------------------------------[ jar ]---------------------------------
    [INFO] 
    [INFO] --- clean:3.2.0:clean (default-clean) @ pile-lang ---
    [INFO] Deleting /Users/onetom/github.com/sixfootbeard/pile/target
    [INFO] 
    [INFO] --- resources:3.3.1:resources (default-resources) @ pile-lang ---
    [WARNING] Using platform encoding (UTF-8 actually) to copy filtered resources, i.e. build is platform dependent!
    [INFO] Copying 8 resources from src/main/pile to target/classes
    [INFO] 
    [INFO] --- compiler:3.10.1:compile (default-compile) @ pile-lang ---
    [INFO] Changes detected - recompiling the module!
    [WARNING] File encoding has not been set, using platform encoding UTF-8, i.e. build is platform dependent!
    [INFO] Compiling 294 source files to /Users/onetom/github.com/sixfootbeard/pile/target/classes
    [INFO] ------------------------------------------------------------------------
    [INFO] BUILD FAILURE
    [INFO] ------------------------------------------------------------------------
    [INFO] Total time:  0.358 s
    [INFO] Finished at: 2023-09-20T03:53:30+08:00
    [INFO] ------------------------------------------------------------------------
    [ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.10.1:compile (default-compile) on project pile-lang: Fatal error compiling: error: release version 20 not supported -> [Help 1]
    [ERROR] 
    [ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
    [ERROR] Re-run Maven using the -X switch to enable full debug logging.
    [ERROR] 
    [ERROR] For more information about the errors and possible solutions, please read the following articles:
    [ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionException
    ./repl  2.37s user 0.18s system 236% cpu 1.075 total

As for your build error I've only seen that with mismatched Java versions. If I run the repl (which is just a single mvn command) with JAVA_HOME pointing to jdk 19 I get the same error. But, I can see obviously you've installed jdk 20 and shown the version. I am unfamiliar with how nix sets up the environment, but is it possible it's running mvn with a different JDK than the version 20 you installed? The seems like it would be the most likely cause.