fennel1

Usage

Overview

This manual page documents briefly the fennel command.

fennel is the main entry point for Fennel, a lisp programming language that runs on Lua runtimes. With no options or arguments, it runs an interactive Read-Eval-Print loop (REPL).

Given a filename as its first argument, it runs that file and passes it the subsequent arguments. Ahead-of-time compilation can be invoked with the --compile flag, while short snippets can be evaluated with the --eval argument.

Options

A summary of options is included below.

--repl

Start an interactive repl session. This is the default when given no arguments.

--compile filename

Perform ahead-of-time compilation on the provided file and write the Lua output to standard out.

--eval source

Evaluate a given piece of source code and print the result.

--no-searcher

When running a repl or a file, fennel.searcher is installed by default so that the require function can load Fennel files in addition to Lua files. This flag disables that behavior. Has no effect for ahead-of-time compilation.

--add-package-path path

Add the given path to package.path so that the require function will know to look there when searching for Lua modules.

--add-fennel-path path

Same as above, but for Fennel's path used when searching for Fennel modules.

--globals VAR1[,VAR2...]

Allow VAR1, VAR2, etc as globals in addition to the standard set of globals. This enables strict global checking even in ahead-of-time compilation where it otherwise would be disabled. Use "*" to disable globals checking.

--globals-only VAR1[,VAR2...]

Same as above, but without the inclusion of the standard set of globals.

--require-as-include

Instead of loading required modules at runtime, compile them inline into the main file being compiled. Only useful during ahead-of-time compilation.

--to-be-closed

When compiling with-open use the to-be-closed feature of Lua 5.4+ to avoid interfering with traces.

--assert-as-repl

Calls to the built-in function assert from Fennel will be replaced with calls to assert-repl so that when the assertion fails, a REPL will be started in which you can interactively debug.

--lambda-as-fn

Replace lambda function definitions with fn, removing the runtime overhead from arity checking.

--use-bit-lib

Compile bitwise operations to use LuaJIT's bitop library instead of Lua 5.3+ bitwise operators.

--load FILE

Load the specified file before any command is run.

--compile-binary FILE OUT LUA_LIB LUA_DIR

Compile FILE to a standalone binary OUT using LUA_LIB and the Lua header files in LUA_DIR. See --compile-binary --help for details.

--no-compiler-sandbox

Do not limit compiler environment (used in macros) to minimal sandbox.

--keywords KEYWORD1[,KEYWORD2...]

Treat these symbols as reserved Lua keywords.

-h, --help

Print a help message and exit

-v, --version

Print the version number and exit

Use the NO_COLOR environment variable to disable escape codes in error messages.

Community

The mailing list is at https://lists.sr.ht/~technomancy/fennel while the issue tracker is at https://dev.fennel-lang.org. Most discussion happens on the #fennel channel of Libera chat.