NAME
fennel - a lisp programming language that runs on Lua
SYNOPSIS
fennel [--repl] | [--compile filename] | [--eval source] | [filename] [args ...]
DESCRIPTION
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.
SEE ALSO
fennel-api(3), fennel-reference(5), fennel-tutorial(7)
The semantics are very close to Lua, so Lua's reference manual is also helpful.
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.
AUTHORS
Calvin Rose and Phil Hagelberg and contributors: https://github.com/bakpakin/Fennel/graphs/contributors
LICENSE
Copyright © 2016-2025, Released under the MIT/X11 license