Kobol Language Support
Full IDE support for Kobol — a modern, COBOL-inspired
language for the JVM. Business-logic clarity with first-class types, fixed-point decimals,
concurrency, and testing.
This extension turns VS Code into a complete Kobol workbench: live diagnostics, go-to-definition,
hover types, signature help, code actions, inlay hints, an outline, and one-key build / run / test.
Features
| Capability |
What you get |
| Syntax highlighting |
TextMate grammar for keywords, types, strings, numbers, -- line comments, NOTE: … END-NOTE block comments, and TODO/FIXME/HACK/XXX tags |
| Live diagnostics |
Errors and warnings from the Kobol compiler as you type, with "did you mean?" suggestions |
| Navigation |
Go-to-definition, hover types, document outline, folding |
| Editing aids |
Signature help, code actions, inlay type hints for LET, auto-indent on : and END-* |
| Status bar |
Per-file error / warning count — click to open Problems |
| Build integration |
Build, Run, Test, Type-Check, Clean commands wired to Gradle or the kobol CLI |
| Snippets |
40+ scaffolds — programs, records, procedures, MATCH, TRY/ON, SERVER, pipelines, JDBC, HTTP, tests |
Requirements
The extension starts a Kobol language server. It resolves one of these, in order:
- Native binary —
kobol.nativeBinaryPath, a bundled bin/kobol, a cached download, or
auto-downloaded from GitHub Releases for your platform.
- JVM fat-jar —
kobol.kobolcJar, a bundled kobolc.jar, or auto-located at
compiler/build/libs/kobolc.jar in your workspace. Requires a JDK 21+ on PATH
(or set kobol.javaExecutable).
To build the jar from the Kobol repo:
./gradlew :compiler:jar
Commands
All commands live under the Kobol: category in the Command Palette.
| Command |
Default keybinding |
| Kobol: Build Project |
Ctrl+Shift+B (on .kbl) |
| Kobol: Run Project |
— |
| Kobol: Run Tests |
— |
| Kobol: Type-Check Only |
— |
| Kobol: Clean Build Output |
— |
| Kobol: Restart Language Server |
— |
| Kobol: Show Version |
— |
A play button also appears in the editor title bar for .kbl files.
Settings
| Setting |
Default |
Description |
kobol.kobolcJar |
"" |
Path to kobolc.jar. Empty → auto-locate in the workspace. |
kobol.javaExecutable |
"java" |
Java used to launch the server in JVM mode. |
kobol.nativeBinaryPath |
"" |
Path to the native kobol binary. Empty → auto-download. |
kobol.buildTool |
"auto" |
gradle, kobol-cli, or auto (Gradle if build.gradle.kts is present). |
kobol.inlayHints.enabled |
true |
Show inferred types for LET declarations. |
kobol.trace.server |
"off" |
Trace LSP messages (off / messages / verbose). |
Quick start
- Open a folder containing
.kbl files.
- Build the compiler jar (
./gradlew :compiler:jar) or point kobol.kobolcJar at one.
- Open a
.kbl file — diagnostics and highlighting activate automatically.
- Press
Ctrl+Shift+B to build, or pick Kobol: Run Project from the palette.
Snippets
Type a prefix and press Tab. A few highlights:
| Prefix |
Expands to |
prog |
Full program scaffold |
proc / procp |
Procedure (with/without params) |
rec |
RECORD definition |
note |
NOTE: … END-NOTE block comment |
match |
MATCH with WHEN / OTHERWISE |
try |
TRY / ON handler |
server |
HTTP SERVER block |
pipe |
Collection pipeline (FILTER → SORT → TAKE) |
test |
Unit TEST block |
Contributing
Issues and PRs welcome at the Kobol repository.
Run the extension locally with F5 (Extension Development Host) — it opens the examples/
folder with the dev build attached.
License
Apache-2.0
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