Quick Tour of Temper#

Temper is a programming language and toolchain for making libraries that can be used natively from any other language.

Temper compiles to idiomatic types and functions for each target language: currently C++, C#, Java, JavaScript, Lua, Python, and Rust, with plans for many more. Whether you're an open-source developer or work in an enterprise, Temper can multiply the reach and effect of your work. "Why a new programming language?" explains what Temper lets you do that existing languages don't.

Get started, or see examples below for a quick tour.

Examples#

Translate#

Temper lets you define rich data types and logic that translate to all supported backend languages. Usage is idiomatic in each language.

export class Person(
  public birthDate: Date,
) {
  public ageAt(date: Date): Int {
    // Or support other definitions of age.
    Date.yearsBetween(birthDate, date)
  }
}

Use from:

Note: these snippets construct a Date exported by the library itself. With std/temporal's Date, each language would use its own date type, such as DateTime in C#, LocalDate in Java, and datetime.date in Python (inconsistencies).

C# 
using Snippets.Person;

var person = new Person(new Date(1987, 6, 5));
var age = person.AgeAt(new Date(2023, 2, 1));
Console.WriteLine($"Age: {age}");
Java 
import snippets.person.*;

class Use {
    public static void main(String[] args) {
        var person = new Person(new Date(1987, 6, 5));
        var age = person.ageAt(new Date(2023, 2, 1));
        System.out.printf("Age: %s\n", age);
    }
}
JS / TS 
import { Date, Person } from "snippets/person.js";

let person = new Person(new Date(1987, 6, 5));
let age = person.ageAt(new Date(2023, 2, 1));
console.log(`Age: ${age}`);
Lua 
local p = require("snippets.person")

local person = p.Person(p.Date(1987, 6, 5));
local age = person:ageAt(p.Date(2023, 2, 1));
print("Age: " .. math.floor(age));
Python 
from snippets.person import Date, Person

person = Person(Date(1987, 6, 5))
age = person.age_at(Date(2023, 2, 1))
print(f"Age: {age}")

Dispatch#

Use interfaces for abstraction. And use familiar syntax.

export interface Shape {
  public perimeter(): Float64;
}

export class Rectangle(
  public width: Float64,
  public height: Float64,
) extends Shape {
  public perimeter(): Float64 { 2.0 * (width + height) }
}

let tau = 2.0 * Float64.pi;

export class Circle(
  public radius: Float64,
) extends Shape {
  public perimeter(): Float64 { tau * radius }
}

When#

Or match on types instead of using virtual dispatch.

export let area(shape: Shape): Float64 {
  when (shape) {
    is Rectangle -> shape.width * shape.height;
    is Circle -> do {
      let { radius } = shape;
      0.5 * tau * radius * radius
    }
    else -> NaN; // needed until exhaustiveness checks
  }
}

Test#

Test your code across languages. Temper test integrates with well-known frameworks such as JUnit, Mocha, and Pytest. You can test your libraries in Temper to build confidence in its correctness and also build confidence in each translation's fidelity.

test("age") {
  let person = new Person(new Date(1987, 6, 5));
  let age = person.ageAt(new Date(2023, 2, 1));
  // You can give a custom failure message callback.
  assert(age == 35) { "Bad age: ${age}" }
  // Or just use automatic messaging.
  // Reports "expected age == (36) not (35)"
  assert(age == 36);
}

Document#

Embed your Temper code inside of Markdown. Collaborate with others on lightweight standards documents that include a reference implementation. Translate the implementation to many programming languages.

## Circle

Tau (τ) is a full turn in radians, rather than the half turn of pi (π).

    let τ = 2.0 * Float64.pi;

    export class Circle(
      public radius: Float64,
    ) {

Using `τ` rather than `π` simplifies some calculations and complicates
others.

      public perimeter(): Float64 { τ * radius }
    }

Develop#

Temper has a language server and an extension for Visual Studio Code (editors). Great tooling helps Temper users discover language features and iterate quickly, so we'll continue to prioritize it.

Screenshot of VSCode with Temper code highlighted starting with red error squiggles under "Float" in public radius: Float and a hover box noting "No declaration for Float". Elsewhere "Float64" appears without error squiggles.

Next steps#

Excited about Temper?

Problems, Questions, Discussion?#