Environment setup

Environment setup

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Environment setup

Please download the program package from the official website. There are two files in the package, one bt program and one bt-app program.

  • bt is a BT language interpreter, used to compile and run BT language programs.
  • bt-app is a BT desktop application engine (built-in BT language interpreter) for desktop software development.

If you need to develop Web projects and API interfaces, you only need bt. If you need to develop desktop application projects, you only need bt-app.

You can keep the interpreter beside your project and run it directly, or install it for your user account as described below. A plain text editor is sufficient to write BT programs.

Install the interpreter

Availability: the installation commands below are pending the next release and require a build containing this feature. Existing release downloads may not yet support them.

Function

Explicitly install the currently running interpreter into a fixed user directory, configure the user PATH, and register .bt files for desktop execution. Installation is optional and does not require an administrator account. Opening the interpreter or running a script never installs or updates BT automatically.

Syntax

In Windows PowerShell, run from the extracted directory:

On Linux or macOS, run from the extracted directory:

If necessary, first grant execution permission with chmod +x bt. At the bt> interactive prompt, enter install or update without the executable prefix. The former --install alias has been removed.

Parameters

CommandArgumentsMeaning
bt installNoneInstall or update the currently running interpreter for this user.
bt updateNoneDownload and update an existing user installation to the latest stable release from the official website.
bt update <name> [--project <dir>]An installed extension name is required; the project directory is optional.Update an official extension without downgrading; see extension updates.
bt install <name> [version] [--project <dir>]An extension name is required. Version and project directory are optional.Install an official extension; see extension installation.

Interpreter installation and updates accept no destination or version parameter. install copies the running interpreter and never downloads another version. update requires an existing installation and fetches the latest stable Windows x64, Linux x64, macOS ARM64, or macOS x64 ZIP directly from the official website, using the published size and SHA-256 digest. It checks the extracted interpreter version before replacement and never downgrades an equal or newer installation. It updates only the installed bt, not bt-app or the portable executable from which the command was invoked.

Result

The command reports installation or retention of the existing interpreter and platform integration results. Failures are reported in the terminal. It is a command-line operation and does not return a BT language value.

PlatformInstalled interpreterDesktop integration
Windows%USERPROFILE%\.bt\bin\bt.exeUser registry entries for PATH and .bt file associations.
Linux~/.local/bin/btUser shell PATH; a terminal .desktop launcher and MIME association when a desktop session is available. Headless systems skip desktop integration.
macOS~/.bt/bin/btUser shell PATH; generated ~/Applications/BT.app receives .bt files from Finder and opens Terminal.

Open a new terminal after installation so it can load the updated PATH. The interpreter remains an independent binary. On macOS, BT.app is a generated desktop helper, not the bt-app desktop application runtime; the download ZIP does not need to contain this helper.

Example

Save this as demo.bt:

After installation, open a new terminal and execute bt demo.bt. You can also select BT as the default application for .bt files and double-click demo.bt: a terminal displays the output and waits for Enter after the script finishes. See usage.

Online update example

After installation, run bt update, or enter update at the bt> prompt. Success prints the old and new versions and installed path; an equal or newer installed version reports that it is up to date. A missing installation reports that bt install is required. Command-line failures return a nonzero exit status; interactive failures keep the session open.

Notes

  • A missing installed interpreter is copied from the running executable. A newer semantic version replaces the installed binary; the same or an older version preserves it. A downloaded older interpreter still runs its own version when opened directly. File associations use the fixed installed path.
  • Online updates preserve the old interpreter if the network request, archive integrity check, extraction, or version verification fails. Downloads and extraction are bounded to 512 MiB; release metadata is bounded to 2 MiB. Metadata requests time out after 30 seconds and archive downloads after 10 minutes. Ordinary runs never contact the update server.
  • Windows online updates can rename the running interpreter before publishing the new binary, retaining at most one .bt-update-previous.exe in the installation directory until it can be removed. Close an older retained session before another update if requested. Existing sessions continue on their original version; newly launched commands use the new version. No process is forcibly stopped.
  • On Windows, an installed interpreter that is still in use may be locked. A failed replacement preserves it; close programs using the installed BT and retry installation from the downloaded interpreter. The installer does not forcibly terminate running programs.
  • On Linux/macOS, a manually changed installer-managed PATH block is reported for repair rather than overwritten. File or profile permissions can leave installation only partly configured. Correct the reported problem and rerun install to complete integration.
  • User PATH makes bt discoverable in a terminal; file associations separately enable double-click execution. Another executable earlier in the terminal's search path may still take precedence; use the full installed path when selecting an exact interpreter.
  • The operating system may require you to choose BT as the default application once. Existing explicit user choices are respected. Linux double-click execution requires a desktop environment and a compatible terminal; macOS may require permission for the helper to control Terminal.
  • Ordinary invocations perform no installation-directory, installed-version, or installation-related PATH checks and add no exit pause. Only explicit install or update starts installation or update work.
  • Desktop execution waits for Enter after normal completion, errors, or exit(). It does not edit the source or append pause(); it does not pause a still-running service or protect against closing the terminal itself.

Code editor:

VS Code + bt-lang extension: open the bt-lang extension directly in VS Code.

bt-lang extension support:

  • Support BT language keywords, functions, strings, etc. highlighting
  • Intelligent code completion and context-aware completion
  • Display the parameter list and current parameter position when calling a function
- Display complete description, parameter and return value information when the mouse hovers over a function

- Support cross-file function jumps to quickly locate definition locations

- Automatically scan and index functions in all BT files

- Automatically identify and parse function definitions in include files

- Display the function structure of the current file in the sidebar

- Support system function prompts and automatic completion

- Quickly execute the BT program in the current workspace

Other editors: