Evergreen Language Introduces Provably Safe Systems Programming with Invariants

Introduction of Evergreen Language

Evergreen is a new systems programming language designed with an emphasis on provable safety. The language allows developers to embed formal specifications directly within their code, moving beyond traditional testing methods for ensuring correctness.

Invariants and Compiler Checks

A core feature of Evergreen is the integration of preconditions, postconditions, and data invariants. These are placed alongside the code they describe, acting as explicit obligations. The compiler then checks these obligations, verifying that the code adheres to its specified behavior and data constraints.

Example of Invariant Use

For instance, a function like `increment(n: usize)` can include a `where n < usize::MAX` precondition and an `ensures result > n` postcondition. These statements are not just comments; they are verifiable conditions that the Evergreen compiler will enforce, contributing to the language's goal of provably safe systems programming.