README

Lisp for PHP, macros, persistent data structures, REPL.

Requirements

PHP 8.5 or newer. Linux and macOS are supported: the full compiler, core and PHAR suites run on both in CI, and a failure on either blocks a release. Windows is best effort, running a reduced suite. What a version number promises, and for how long, is in the stability policy.

Get Started

composer require phel-lang/phel-lang

1. Open a REPL

./vendor/bin/phel repl

phel:1:> (->> [1 2 3 4 5] (filter odd?) (map #(* % %)) (reduce +))
35
phel:2:> (defn greet [name] (str "Hello, " name "!"))
| user/greet
phel:3:> (greet "Phel")
| "Hello, Phel!"

2. Scaffold a project

./vendor/bin/phel init         # add `--minimal` for a single-file layout

Creates phel-config.php, src/main.phel, tests/main_test.phel. With --minimal the two sources sit at the project root instead. Then:

./vendor/bin/phel run src/main.phel        # run
./vendor/bin/phel test                     # tests
./vendor/bin/phel build                    # compile to PHP
./vendor/bin/phel config                   # inspect the merged config

3. Eval inline or via stdin

./vendor/bin/phel eval '(+ 1 2)'           # prints 3
echo '(println "hi")' | ./vendor/bin/phel eval -
./vendor/bin/phel eval - < script.phel

4. Enable shell completion (optional)

./vendor/bin/phel completion dumps a tab-completion script for bash, zsh, or fish. It completes commands, their options, and dynamic values (function names for doc, project namespaces for run/test).

# bash — restart your shell afterwards
./vendor/bin/phel completion bash | sudo tee /etc/bash_completion.d/phel

# zsh — write into a directory on your $fpath
./vendor/bin/phel completion zsh > "${fpath[1]}/_phel"

# fish
./vendor/bin/phel completion fish > ~/.config/fish/completions/phel.fish

The zsh script starts with #compdef phel, so completion only triggers for a binary named phel on your $PATH. If you call ./vendor/bin/phel (or ./bin/phel in a dev checkout), symlink a global phel first, e.g. on macOS + Homebrew:

phel completion zsh > "$(brew --prefix)/share/zsh/site-functions/_phel"
ln -sf "$PWD/bin/phel" "$(brew --prefix)/bin/phel"   # global `phel` so #compdef matches
rm -f ~/.zcompdump*                                  # force compinit to rebuild
# then open a new shell

Prefer a project template? web-skeleton or cli-skeleton: click Use this template for a one-click start.

More examples →

Data pipeline

(def users
  [{:name "Ada" :age 36}
   {:name "Bob" :age 17}
   {:name "Cam" :age 41}])

(->> users
     (filter #(>= (:age %) 18))
     (map :name)
     sort)
;; => ["Ada" "Cam"]

HTTP response

(ns app (:require phel.http :as h))

(def req (h/request-from-globals))

(h/emit-response
  (h/response-from-map
    {:status 200
     :headers {"Content-Type" "text/plain"}
     :body (str "Hello " (:uri req))}))

Macros

(defmacro unless [pred & body]
  `(if (not ~pred)
     (do ~@body)))

(unless (zero? 1)
  (println "not zero"))
;; => not zero

(unless false (println "ok"))
;; => ok

PHP interop

(ns app)

(def now (new DateTime))
(.format now "Y-m-d")
;; => "2026-04-20"

(def epoch (new DateTime "1970-01-01"))
(.-days (.diff now epoch))
;; => 20564

Documentation

Getting Started: install, REPL, first script (5 min)
CLI Reference & DX Guide: every command, the dev loop, compile vs eval vs run vs build
phel-lang.org: full documentation, tutorials, exercises, blog
Contributor docs: repository internals, architecture, project layout
Architecture decisions: why the repository is shaped the way it is
Packagist
CONTRIBUTING.md: setup and workflow

AI Coding Agents

Skill files for Claude Code, Cursor, Codex, Gemini, Copilot, Aider: resources/agents/

./vendor/bin/phel agent-install [platform]   # install skill file for one agent (claude, cursor, ...)
./vendor/bin/phel agent-install --auto       # only agents detected in this project
./vendor/bin/phel agent-install --all        # every supported platform

phel-lang / phel-lang

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README

Requirements

Get Started

Documentation

AI Coding Agents