Editor workflow

Use the Forst VS Code extension to edit .ft files with diagnostics, hover, completion, go-to-definition, rename, and formatting. Install the extension, open a project folder, and start editing. The extension downloads the compiler automatically on first use.

1. Install the extension

In VS Code: Extensions → search Forst → Install (Marketplace). In Cursor, VSCodium, or other Open VSX–compatible editors: install **Forst on Open VSX.

2. Open your project

Open a workspace folder that contains .ft files (for example a service repo or the Forst examples/in/ tree). For example, open a file like hello.ft:

Forst
Generated Go

package main

func greet(): String {
	return "Hello, World!"
}

func main() {
	println(greet())
}

// forst build
package main

func greet() string {
	return "Hello, World!"
}

func main() {
	println(greet())
}

The extension starts the language server automatically and fetches the matching forst binary when needed. The status bar shows the LSP port (default 8081) and connection state. Click it to open logs.

What you get while editing

Action	What happens
Open or edit a `.ft` file	Diagnostics update as you type
Hover a symbol	Types, docs, Provider obligations, and Go import signatures (with godoc when available)
Go to definition / Find references	Jump across same-package `.ft` files, cross-package Forst imports in the same module, `import node` bindings to resolved `.ts`/`.js` files, and Go imports to resolved `.go` sources
Rename symbol	Rename across merged package sources
Format document	Format the current file (experimental)
Command palette → Forst	Focus logs or restart the language server

Completion covers keywords, locals, same-package symbols, and members on Go-typed bindings where inference ran. Completion for Go package names after pkg. is not available yet. Go interop in the editor: qualified imports (fmt.Println) and same-package .go functions show go/types signatures; godoc is included when loads succeed. Go to definition jumps into resolved .go sources for import paths, package qualifiers (exec.Command), same-package exports (AddInts), and receiver methods (cmd.Run). Cross-package Forst imports (e.g. Providers auth → api) use module-level typechecking so diagnostics match compile-time arity—not generated Go stubs in the source tree. See Go interop. Node interop in the editor: import node path strings, module aliases, and qualified calls (payment.create) support go to definition into the resolved TypeScript or JavaScript module. Export names jump to the indexed symbol when the compiler has indexed the module. See Node interop.

Settings

Change these in VS Code → Settings when the defaults do not match your setup:

Setting	Default	When to change
`forst.compiler.path`	(empty)	Point at a specific `forst` binary (local build, CI cache)
`forst.compiler.download`	`true`	Set `false` if you only want `PATH` or workspace `bin/forst`
`forst.lsp.autoStart`	`true`	Set `false` if you run `forst lsp` yourself
`forst.lsp.port`	`8081`	Use a different port when 8081 is taken

Commands

Forst: Focus output: open the LSP log channel
Forst: Restart language server: use after upgrading the compiler or when diagnostics look stale

Troubleshooting

No diagnostics on .ft files: confirm the language mode is Forst (not Plain Text). Run Forst: Restart language server and check the Forst output channel. Stale errors after a compiler upgrade: run Forst: Restart language server, or set forst.compiler.path to your new bin/forst. Parse errors on Providers syntax: update to a recent compiler build. Providers shapes need current parser support.

Forst on Marketplace

Install in VS Code.

Forst on Open VSX

Install in Cursor, VSCodium, and other Open VSX editors.

CLI reference

Run forst from the terminal, including forst lsp.

Overview

Getting started

Data validation

Behavior

Interop

Workflow

Editor workflow

1. Install the extension

2. Open your project

What you get while editing

Settings

Commands

Troubleshooting

Forst on Marketplace

Forst on Open VSX

CLI reference

​1. Install the extension

​2. Open your project

​What you get while editing

​Settings

​Commands

​Troubleshooting

​Related

Forst on Marketplace

Forst on Open VSX

CLI reference

1. Install the extension

2. Open your project

What you get while editing

Settings

Commands

Troubleshooting

Related