Clove

Japanese version: README.ja.md

Clove is a small language inspired by Clojure-style S-expressions, with lightweight types (deftype / defenum), pattern matching, and even Ruby / Python embedding in one place.

It keeps the Clojure-like feel while letting you mix in the outside world (Ruby/Python) when it matters. That is the "flavor" we aim for.

Status: experimental / WIP — syntax, APIs, and CLI can change. Specs live in docs/, runnable code in examples/. This README is intentionally short and example-focused.

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Quick taste

Hello

(ns examples::hello)

(println "Hello from Clove!")

clove examples/hello.clv

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Dot-chain (.(...)) and placeholder ?

You can write as->-style flows as expr.( ... ). ? is the placeholder for the previous value.

(inc 123).(+ 1 ?).(repeat 3 ?).(map inc ?)
; => (126 126 126)

*? expands the previous value as args (internally apply).

[inc (range 10)].(map *?)
; => (1 2 3 4 5 6 7 8 9 10)

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Placeholder ? (inline function)

Any expression that includes ? becomes a small inline function.

(map (+ ? 10) (range 5))
; => (10 11 12 13 14)

(filter (not= :skip ?) [:ok :skip :ok])
; => (:ok :ok)

For details, see docs/language/reader_syntax.md.

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Map shorthand + indexer ([])

Alongside Clojure-style {:x 1}, JSON-like {name: "Taro"} is supported.

(def user {name: "Taro" age: 30})
user[:name] ; => "Taro"

Indexers are flexible beyond simple lookup:

(def xs [10 11 12 13 14 15])

xs[0]        ; => 10
xs[-1]       ; => 15
xs[99 || :ng]; => :ng   ; default when missing

xs[[0 2 4]]  ; => [10 12 14]  ; gather
xs[1,5,7]    ; => [11 15 17]  ; multiple indexes
xs[..3]      ; => [10 11 12 13] ; open range
xs[2..]      ; => [12 13 14 15]
xs[1...3]    ; => [11 12]       ; end-exclusive

xs[(+ 1 2)]  ; => 13  ; expressions inside indexer

Details (range, -foo rule, map/set/get-in, etc.) are in docs/language/indexer.md.

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deftype / defenum / match (lightweight types + branching)

We emphasize data + pattern matching instead of protocols/multimethods.

(deftype Dog  {:name :string :age :int})
(deftype Cat  {:name :string :lives :int})
(defenum Pet Dog Cat)

(defn pet-name [p]
  (match p
    (Dog {:name n}) n
    (Cat {:name n}) n))

(pet-name (Dog {:name "Pochi" :age 3}))
; => "Pochi"

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Mix Ruby / Python inline

One of Clove's unique features is embedding external languages. Ruby is the default external language, so use $rb{...} (or ${...} as an alias).

(defn ruby-version []
  $rb{ RUBY_VERSION })

(defn py-sqrt [x]
  $py{
    import math
    math.sqrt(x)
  })

(println (ruby-version))
(println (py-sqrt 9)) ; => 3.0

JSON/YAML can also be read via reader tags.

(def config
  #json{"host":"localhost","port":8080})

config[:host] ; => "localhost"

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Concurrency primitives (minimal)

We include atom / chan / promise / task / future / agent.

(def c (chan 1))
(chan-put! c :ok)
(chan-take! c) ; => :ok

More examples are in examples/concurrency/ and docs/language/concurrency.md.

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Where to read next

• Quick start: docs/getting_started.md

• Docs entry: docs/index.md

• Examples: examples/

• Run examples:

  clove --main examples/concurrency/async_scope_nested.clv

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Install / Build

Most reliable (from source)

Currently developed as a Rust workspace.

git clone https://github.com/inakaegg/clove-lang clove
cd clove
cargo build -p clove-lang --release
./target/release/clove --help

To install to PATH:

cargo install --path crates/clove-lang --force
clove --repl

If Rust is installed (without cloning)

cargo install --git https://github.com/inakaegg/clove-lang --locked --package clove-lang --bin clove

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License

Dual-licensed under MIT or Apache-2.0, at your option.
See LICENSE-MIT and LICENSE-APACHE.