Gleam (programming language)

Gleam

Lucy, the starfish mascot for Gleam
Paradigm	Multi-paradigm: functional, concurrent
Designed by	Louis Pilfold
Developer	Louis Pilfold
First appeared	June 13, 2016 (2016-06-13)
Stable release	1.6.1  / 19 November 2024
Typing discipline	Type-safe, static, inferred
Memory management	Garbage collected
Implementation language	Rust
OS	FreeBSD, Linux, macOS, OpenBSD, Windows
License	Apache License 2.0
Filename extensions	.gleam
Website	gleam.run
Influenced by
Alpaca Elm Erlang Elixir Go JavaScript OCaml Rust

Gleam is a general-purpose, concurrent, functional high-level programming language that compiles to Erlang or JavaScript source code.

Gleam is a statically-typed language, which is different from the most popular languages that run on Erlang’s virtual machine BEAM, Erlang and Elixir. Gleam has its own type-safe implementation of OTP, Erlang's actor framework. Packages are provided using the Hex package manager, and an index for finding packages written for Gleam is available.

History

The first numbered version of Gleam was released on April 15, 2019. Compiling to JavaScript was introduced with version v0.16.

In 2023 the Erlang Ecosystem Foundation funded the creation of a course for learning Gleam on the learning platform Exercism.

Version v1.0.0 was released on March 4, 2024.

Features

Gleam includes the following features, many common to other functional programming languages:

• Result type for error handling
• Immutable objects
• Algebraic data types
• Pattern matching
• No null pointers
• No implicit type conversions

Example

A "Hello, World!" example:

import gleam/io

pub fn main() {
  io.println("hello, friend!")
}

Gleam supports tail call optimization:

pub fn factorial(x: Int) -> Int {
  // The public function calls the private tail recursive function
  factorial_loop(x, 1)
}

fn factorial_loop(x: Int, accumulator: Int) -> Int {
  case x {
    1 -> accumulator

    // The last thing this function does is call itself
    _ -> factorial_loop(x - 1, accumulator * x)
  }
}

Implementation

Gleam's toolchain is implemented in the Rust programming language. The toolchain is a single native binary executable which contains the compiler, build tool, package manager, source code formatter, and language server. A WebAssembly binary containing the Gleam compiler is also available, enabling Gleam code to be compiled within a web browser.

External links

• Official website
• Gleam-lang on GitHub