java

Rúnar Java Compiler

Reference implementation of the Rúnar compiler pipeline in Java. Compiles .runar.java (and the other Rúnar input formats, once milestone 7 lands) to Bitcoin SV Script, producing byte-identical output to the other six compilers in this repository.

Status

Production. Full pipeline is wired (parse → validate → expand-fixed-arrays → typecheck → ANF lower → optional constant-fold → ANF cleanup → stack lower → peephole → emit). All 9 input formats parse via ParserDispatch. Conformance runner, fuzzer differential harness, and cross-compiler hex-equality tests include this binary alongside the other six tiers. See docs/java-tier-plan.md for the milestone history.

Requirements

• JDK 17 (compile target). JDK 21 LTS works for local development.
• The Gradle wrapper (gradlew / gradlew.bat) is committed at Gradle 8.5, so no system gradle install is required. The wrapper downloads its pinned distribution on first invocation.

Build & Run

cd compilers/java
./gradlew build              # compile + run tests
./gradlew installDist        # produce an executable layout under build/install/
./build/install/runar-java-compiler/bin/runar-java --version

CLI Contract

Every Rúnar compiler binary must accept the following flags. The Java CLI implements all of these end-to-end.

Flag combination	Behavior
--source <path> --emit-ir --disable-constant-folding	Emit canonical ANF JSON on stdout
--source <path> --hex --disable-constant-folding	Emit Bitcoin Script hex on stdout
--ir <path> --hex	Compile a pre-generated ANF JSON to hex
--version	Print runar-java x.y.z

The Java CLI also accepts these, which this table used to omit entirely (R-232). --parse-only was additionally missing from --help, so it was a working flag no output mentioned:

Flag	Behavior
--parse-only	Run passes 1-2 only and print parser ok. Used by the conformance runner's all-tier parser-only matrix
--emit-ir-to <path>	Write the same ANF JSON --emit-ir prints to a file and KEEP compiling, so one process yields both artefacts
--emit-source-map <path>	Write the artifact's sourceMap JSON to a path; runs independently of --emit-ir / --hex
--emit-artifact <path>	Write the deployable artifact JSON to a path
--daemon	Line-delimited JSON RPC on stdin/stdout, for the conformance runner's Java daemon
-h, --help	Print the flag list and exit

tests/r232-java-cli-flags-documented.test.ts keeps both surfaces honest: every flag the CLI accepts must appear in --help and in this table.

The conformance runner at conformance/runner/runner.ts exercises this contract once the binary is registered there (milestone 4).