starlarkt

Implementation of Starlark in pure Kotlin.

Starlark is strongly influenced by Python, Starlark syntax is a strict subset of Python, and Starlark semantics is almost a subset of that language.

– Starlark spec

Goals

• works
• passes upstream test suite even
• pure Kotlin Multiplatform (no dependency on the JVM)
• simplicity of implementation
• well-documented and reasonably clean code

Non-goals

• performance

  starlarkt is currently a tree-walk interpreter. The Go implementation of Starlark is a bytecode virtual machine. In the future a bytecode virtual machine may be implemented for starlarkt, but it's not deemed important.

Resources

• overview
• Starlark implementation in Go by Google:
  • spec (Bazel (official?) version)
  • spec (Go version), including grammar
  • implementation doc
• Starlark implementation in Java by Google
  • spec (Java version), including grammar
  • PR: explicitly state that Starlark syntax is a strict subset of Python
• Starlark implementation in Rust by Facebook
• test suite
• language design
• awesome-starlark

Yes, the useful info is kinda all over the place.

Development

Practices

• Follow Kotlin coding conventions
• Follow Kotlin best practices for library designers
• Follow Semantic Line Breaks

Native executable

Build a native executable (here, Apple Silicon):

$ ./gradlew :app:linkDebugExecutableMacosArm64

Run it:

$ ./app/build/bin/macosArm64/debugExecutable/starlarkt.kexe

JVM

Build a JVM jar and startup script:

$ ./gradlew :app:installJvmDist

Run it:

$ ./app/build/install/app-jvm/bin/app

Tests

Run tests (on JVM, because it supports JUnit, which has more cool features than plain kotlin.test):

$ ./gradlew :interpreter:jvmTest