v0.2.0

A little magic in every line of code.

Pooka is a small, statically typed language for the BEAM. Immutable classes, interfaces, enums, pattern matching and actors, with errors you can hold in your hand, and good manners towards Erlang, Elixir and Gleam.

Get started Take the tour

$ curl -fsSL https://pooka.run/install.sh | sh

On Windows? Follow the installation guide.

src/main.pooka

module main

import pooka/io
import pooka/list

class Lantern(name: String, lit: Bool)

glow(lantern: Lantern) -> String {
  match lantern.lit {
    True -> lantern.name + " is glowing"
    False -> lantern.name + " waits in the dark"
  }
}

main() {
  [Lantern("Ada", True), Lantern("Bo", False)]
  |> list.map(glow)
  |> list.each(fn(line: String) {
    let _ = io.println(line)
    Nil
  })
}

pooka run
   Compiled 1 module in 0.41s
    Running lantern.main
Ada is glowing
Bo waits in the dark

Pooka, a small dark creature with glowing eyes and an orange scarf, holding a lantern

01 Quick start

From nothing to running in a minute.

Make a project

A pooka.toml, a src/main.pooka and a first test.

pooka new lantern
cd lantern

Run it

Dependencies download, modules compile, main() runs.

pooka run
pooka test

Bring friends

Any Hex package works: Pooka, Erlang, Elixir or Gleam.

pooka add arglet
pooka add cowboy

02 A short walk

Read it once, remember it.

Every example below compiles and runs with Pooka 0.2.0.

classes.pooka

module main

class Creature {
  let name: String

  new(name: String) {
    self.name = name
  }

  greet() -> String {
    "..."
  }
}

class Owl is Creature {
  new(name: String) {
    super.new(name)
  }

  greet() -> String {
    "hoo"
  }
}

main() {
  let owl: Creature = Owl("Ada")
  echo owl.name + " says " + owl.greet()
}

pooka run
src/main.pooka:27
"Ada says hoo"

enums.pooka

module main

enum Weather {
  Sunny,
  Rainy,
  Foggy
}

plan(weather: Weather) -> String {
  match weather {
    Weather.Sunny -> "walk to the harbour"
    Weather.Rainy -> "write a parser"
    Weather.Foggy -> "listen for the lighthouse"
  }
}

main() {
  echo plan(Weather.Rainy)
}

pooka run
src/main.pooka:18
"write a parser"

pipelines.pooka

module main

import pooka/int
import pooka/list
import pooka/string

main() {
  [3, 1, 2]
  |> list.sort
  |> list.map(int.to_string)
  |> string.join(", ")
  |> echo
}

pooka run
src/main.pooka:12
"1, 2, 3"

results.pooka

module main

import pooka/int

parse_cups(text: String) -> Result(Int, String) {
  match int.parse(text) {
    Ok(cups) if cups > 0 -> Ok(cups)
    Ok(_) -> Error("at least one cup, please")
    Error(_) -> Error("`" + text + "` is not a number")
  }
}

brew(text: String) -> Result(String, String) {
  let cups = parse_cups(text)?
  Ok(int.to_string(cups) + " cups brewing")
}

main() {
  echo brew("3")
  echo brew("lots")
}

pooka run
src/main.pooka:19
Ok("3 cups brewing")
src/main.pooka:20
Error("`lots` is not a number")

actors.pooka

module main

actor Kettle {
  var cups: Int = 0

  be pour(count: Int) {
    cups += count
  }

  poured() -> Int {
    cups
  }
}

main() {
  let kettle = Kettle()
  kettle.pour(2)
  kettle.pour(1)
  echo kettle.poured()
}

pooka run
src/main.pooka:19
3

interop.pooka

module main

external Math from erlang "math" {
  sqrt(x: Float) -> Float

  pi() -> Float
}

main() {
  echo Math.sqrt(2.0)
  echo Math.pi()
}

pooka run
src/main.pooka:10
1.4142135623730951
src/main.pooka:11
3.141592653589793

pooka build

error: non-exhaustive match
   ╭─ src/main.pooka:16:9
   │
16 │   match weather {
   │         ───┬───
   │            ╰─ not every main.Weather value is handled
   ╰─

Every possible value of the matched type must be handled.

help: Handle `Weather.Foggy` or add a fallback branch.

03 Diagnostics

Errors that help.

When something is wrong, Pooka points at it, says why, and suggests what to do next.

✓
LocatedFile, line and column, with the source right there.
✓
ExplainedA sentence about the rule, not just the symptom.
✓
ActionableA help: line naming the missing case or the likely fix.

Light the lantern.

Install Pooka, make a project, and say hello to the BEAM. The tour takes an evening; the cookbook is there whenever you're hungry.

Install Pooka Open the cookbook