Try Kex in your browser on kex.run

Kex Language Support for VS Code

Syntax highlighting, type-aware hover, completion, navigation, and live compiler diagnostics for Kex.

Kex is a functional language with Ruby-like syntax, immutability by default, UFCS function chains, and an Elixir-style process model. Try the language in your browser at kex.run.

The extension is a thin client. Everything it shows comes from the Kex compiler itself, running as a language server (kex --lsp), so hover types and diagnostics are the compiler's own answers rather than a separate model of the language that could drift from it.

Hover on an overloaded function, showing which overload was selected, the others available, and the documented example

Completion after a dot in a builder chain, listing each function with its full signature

Features

Type and declaration hover — the declaration as written, plus any doc comments above it. On an overloaded function it names the overload chosen at that call site and lists the alternatives.
Diagnostics as you type — syntax, type, and validation errors on the unsaved buffer, not just on save.
Completion — functions after ., and top-level names, with signatures and overload counts.
Go to definition and find references.
Syntax highlighting for Kex's full grammar.
Automatic server restart when the configured compiler is rebuilt inside the workspace.

Requirements

The extension needs a kex executable. Kex ships with Tey, its toolchain manager, and installing Tey installs a working kex:

brew install kexhq/tey/tey
kex --version

The kex on your PATH is Tey's dispatcher: it runs whichever toolchain Tey has selected, so there is only ever one compiler command.

tey kex list [--pre]        # released and installed versions
tey kex install [<version>] # newest stable, or the one you name
tey kex use <version>       # switch what `kex` runs

Not on macOS or Linux with Homebrew? Build from source — see the repository README — then point kex.executablePath at the binary.

Settings

Setting	Default	Description
`kex.executablePath`	`kex`	Compiler used by the language server. Relative paths resolve from the workspace root, so `build/kex` works when developing Kex itself.

Commands

Command	Description
Kex: Restart Language Server	Restarts the server without reloading the window.

Extension Development

Build Kex from the repository root: cmake --build build --target kex.
In this directory, run bun install and bun run compile.
Open this directory in VS Code and press F5 to launch an Extension Development Host.
Set kex.executablePath to build/kex when developing Kex itself, or install kex on PATH.

The server can also be driven by any LSP client:

kex --lsp

It communicates over standard input/output using LSP Content-Length frames.

When the configured executable is inside the workspace (for example build/kex), rebuilding it automatically restarts the language server. You can also run Kex: Restart Language Server from the command palette.