Helix JVM language setup

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I have been a huge helix fan for some time now. It is my daily coding driver for most languages and environments. Helix support many languages and language servers out of the box and are easy to configure. In this post I’ll step through basic configuration to work with Java and Kotlin in Helix.

Java Development

Install Prerequisites

  • JDK (Java Developer Kit) on your system

  • Install jdtls (Eclipse JDT Language Server) for Java language support

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    # Install Java first if you haven't
    brew install openjdk@21

    # Install Maven (needed for some JDTLS features)
    brew install maven

    # Install jdtls
    brew install jdtls

    # Create Configuration Directory
    mkdir -p ~/.config/jdtls
    mkdir -p ~/.cache/jdtls/workspace

    # Test if JDTLS works
    jdtls --version

  • Configure Helix language support, add to ~/.config/helix/languages.toml

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[language-server.jdtls]
command = "jdtls"
args = ["-data", "~/.cache/jdtls/workspace"]

[[language]]
name = "java"
scope = "source.java"
file-types = ["java"]
roots = ["pom.xml", "build.gradle", ".git"]
language-servers = ["jdtls"]

Kotlin Development

Install Prerequisites

  • Install Kotlin
  • Install Kotlin Language Server
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brew install kotlin
brew install kotlin-language-server
  • Configure Helix language support, add to ~/.config/helix/languages.toml
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[language-server.kotlin]
command = "kotlin-language-server"

[[language]]
name = "kotlin"
scope = "source.kotlin"
injection-regex = "kotlin"
file-types = ["kt", "kts"]
shebangs = ["kotlin"]
roots = ["settings.gradle", "settings.gradle.kts", "build.gradle", "build.gradle.kts"]
comment-token = "//"
language-servers = ["kotlin-language-server"]
indent = { tab-width = 4, unit = "    " }

BONUS Scala Development

Install Prerequisites

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# For macOS
brew install scala
brew install coursier/formulas/coursier
brew install metals  

cs setup
cs install metals
  • Configure Helix language support, add to ~/.config/helix/languages.toml
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[language-server.metals]
command = "metals"
args = []

[[language]]
name = "scala"
scope = "source.scala"
file-types = ["scala", "sbt", "sc"]
roots = ["build.sbt", "build.sc"]
language-servers = ["metals"]
indent = { tab-width = 2, unit = "  " }

Helix Health Report

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❯ hx --health java
Configured language servers:
  ✓ jdtls: /opt/homebrew/bin/jdtls
Configured debug adapter: None
Configured formatter: None
Tree-sitter parser: ✓
Highlight queries: ✓
Textobject queries: ✓
Indent queries: ✓

❯ hx --health kotlin
Configured language servers:
  ✓ kotlin-language-server: /opt/homebrew/bin/kotlin-language-server
Configured debug adapter: None
Configured formatter: None
Tree-sitter parser: ✓
Highlight queries: ✓
Textobject queries: ✘
Indent queries: ✘

❯ hx --health scala
Configured language servers:
  ✓ metals: /opt/homebrew/bin/metals
Configured debug adapter: None
Configured formatter: None
Tree-sitter parser: ✓
Highlight queries: ✓
Textobject queries: ✓
Indent queries: ✓

Debugging support we will leave for a follow up post.