Hare 0.26.0: A New Chapter in Systems Programming with Enhanced Control and Cross-Platform Support

The Hare programming language has reached another significant milestone with the release of version 0.26.0, marking the first stable update since Hare 0.25.2 last year. This release represents not just incremental improvements but meaningful enhancements to the language's expressiveness and control, while simultaneously expanding its reach across operating systems.

At the heart of this release are several carefully considered additions that give Hare programmers more precise control over their code's behavior and structure. The most notable among these is the enhancement of Hare's for loop construct, which has been transformed from a simple iteration mechanism into a powerful expression capable of returning values.

The new loop expression capability introduces two elegant mechanisms for controlling loop outcomes. First, the break statement can now carry a value, allowing immediate termination with a specific result. Second, an optional else branch can be appended to the loop, providing a fallback value when the loop completes without hitting a break statement. This dual approach creates a remarkably expressive pattern for common programming scenarios.

Consider the practical example of searching through a collection: when an item matching a specific key is found, the loop breaks and returns that item; if no match is found, the else branch handles the failure case, perhaps by logging an error and returning early. The type system elegantly handles these scenarios, with the else branch capable of returning never when the function should exit, or a default value when the loop should continue with fallback data.

A real-world implementation from the Hermes kernel demonstrates the power of this feature in systems programming contexts. The scheduler's CPU selection logic uses a for loop to find an idle CPU, breaking with the CPU reference when found, or falling back to random selection when none are available. This pattern replaces what would typically require additional variables and conditional logic with a single, self-contained expression that clearly communicates intent.

Beyond loop enhancements, Hare 0.26.0 addresses several practical needs that arise in systems programming. The language's strict error handling, while generally beneficial, occasionally requires deliberate error ignoring. The new syntax using underscore assignment makes this explicit and clear: _ = os::remove("/some/file"); This approach is more transparent than previous workarounds and signals intentional error suppression to code reviewers and maintainers.

Struct definition has also been improved with the introduction of unnamed fields using underscores for padding. This replaces the cumbersome @offset keyword with a simpler, more intuitive syntax. Programmers can now explicitly control memory layout by inserting padding bytes where needed, improving compatibility with hardware requirements or external data formats. The syntax is straightforward: _: u8, creates a single byte of padding at the desired location within the struct.

The release also introduces explicitly uninitialized variables through the @undefined keyword. While Hare's philosophy emphasizes initialization for safety, certain scenarios in systems programming require declaring variables before they can be meaningfully initialized. This might occur when passing pointers to functions that will perform initialization, or when working with complex data structures that reference objects not yet created. The @undefined keyword provides a clear signal to both the compiler and human readers that the variable's value is intentionally unspecified and will be initialized later. This maintains Hare's safety guarantees while providing the flexibility needed for low-level programming tasks.

Platform support has expanded significantly with the addition of DragonflyBSD, thanks to Michael Neumann's dedicated work. This brings Hare's supported platforms to include Linux and the four most common BSD variants, substantially broadening the language's applicability in the systems programming domain. Michael's continued involvement as the maintainer for this new subsystem ensures ongoing support and optimization for DragonflyBSD users.

The release also marks an organizational milestone with the formal addition of Joe Finney to the maintainer team. Joe's contributions as a reviewer and contributor have been instrumental in shaping Hare's development, and his elevation to maintainer status reflects the project's growth and maturation. His work on the loop expression feature and struct padding improvements demonstrates the kind of thoughtful, practical enhancements that strengthen the language.

These changes collectively represent Hare's evolution toward a more expressive and practical systems programming language while maintaining its core principles of simplicity, robustness, and explicit control. The loop expression feature in particular transforms a basic control structure into a versatile tool for expressing complex logic concisely. The error handling improvements and struct layout controls address real-world needs without compromising the language's safety guarantees.

For developers working in systems programming, Hare 0.26.0 offers compelling new capabilities that reduce boilerplate, improve code clarity, and provide finer control over program behavior. The language continues to strike a careful balance between safety and flexibility, giving programmers the tools they need while maintaining clear, explicit code that is easier to reason about and maintain.

The release is available for download with compiler, standard library, and update tools provided as separate packages. Compatibility with version 1.2 of the QBE compiler backend ensures continued reliability and performance across supported platforms. As Hare continues to mature, releases like 0.26.0 demonstrate the project's commitment to thoughtful, practical improvements that serve the needs of systems programmers while staying true to its design philosophy.

For those new to Hare, the language offers a compelling alternative to C for systems programming, with modern language features, strong typing, and explicit memory management. The 0.26.0 release makes it an even more attractive choice for developers seeking a simpler, safer approach to systems-level development without sacrificing the control and performance that such programming demands.