Discover Fennel: A Lisp‑Based Language for Lua Lovers and Game Creators

This month’s language spotlight is Fennel, a Lisp that runs on Lua and brings the power of s‑expressions to Lua developers.

Fennel uses prefix notation and parentheses, so an addition is written as (+ 2 2) instead of 2 + 2.

The design echoes the original 1950s Lisp ideas: simple syntax, easy code writing, and a macro system that lets you transform code at compile time.

Macros act like functions that rewrite S‑expressions, enabling language extensions without creating a brand‑new language.

Getting Started

You can run Fennel directly in TIC‑80 to build games and generative art without any installation.

Key Features

Fully compatible with Lua: call any Lua function or library from Fennel and vice versa.

Zero overhead: compiled code runs as efficiently as hand‑written Lua.

Compile‑time macros: no runtime dependency on Fennel.

Embeddable: single‑file library or executable that can be embedded for runtime extensibility and interactive development.

Sample Code

;; Sample: read the state of the keyboard and move the player accordingly
(local dirs {:up [0 -1] :down [0 1] :left [-1 0] :right [1 0]})
(each [key [dx dy] (pairs dirs)]
  (when (love.keyboard.isDown key)
    (let [[px py] player
          x (+ px (* dx player.speed dt))
          y (+ py (* dy player.speed dt))]
      (world:move player x y))))

Any environment that can run Lua can also run Fennel code.

Community

The source repository lives on Sourcehut with a read‑only mirror on GitHub; discussions happen on the mailing list, Libera.Chat, and the Matrix #fennel channel.