Summary
Highlights
The speaker contrasts the safety statements of airplane and elevator designers with the trepidation of software engineers regarding computerized voting. He argues that the software field needs improvement and introduces a satirical 'to-do list' for programmers creating poor software, which includes practices like preventing code reuse and using garbage collection.
The speaker outlines problems with common language features such as unpredictable latency from garbage collection, crashes due to automatic heap allocation, slow execution compared to C, and difficulty in ABI interoperation. He also criticizes complex build processes like TensorFlow. He then 'disqualifies' most mainstream languages for these issues, leaving primarily C, C++, and assembly.
Assembly is deemed impractical. C++ is dismissed due to its complexity and features that violate the laid-out principles. C is then scrutinized for issues like 'pound includes' leading to slow compilation and developer frustration, and preprocessor macros that hinder debugging, IDEs, and ABI compatibility. The speaker also highlights C's 'unnecessary undefined behavior' making high-quality software difficult to write.
The speaker introduces Zig as a language that fixes C's problems without adding excessive features. He demonstrates how C code struggles with simple constant calculations due to compiler restrictions and how preprocessor macros are often used as a workaround, leading to unclear and error-prone code.
Zig addresses C's constant evaluation limitations by treating everything as an expression that can be evaluated at compile time. This is shown through examples where array lengths can be determined by functions at compile time using the 'comptime' keyword. This feature allows for powerful compile-time assertions and static elimination of dead code branches, replacing C's problematic preprocessor-based conditional compilation.
By allowing types as compile-time known parameters, Zig inherently supports generics without explicitly designing a complex generics system. This arises naturally from the language's core principles of expression evaluation at compile time.
Zig prioritizes correct error handling, making it the easiest path for developers. An example demonstrates how lazy C code can silently fail, while similar Zig code immediately highlights errors, providing a clear error trace. Zig's error traces combine with stack traces for comprehensive debugging information, especially useful when 'catch unreachable' is violated.
The speaker contrasts Zig's approach to resource cleanup with C's complex nested 'if' statements and 'goto' patterns. Zig's 'defer' and 'errdefer' keywords allow for concise and reliable resource management, ensuring cleanup even in the presence of errors, preventing the 'spaghetti cleanup code' common in other languages.
Zig's error sets enable exhaustive error handling. The compiler can identify all possible errors a function might return, forcing the developer to handle each case. If new error codes are introduced or removed, the compiler informs the developer to update their logic, ensuring robust error handling.
Zig features a built-in, unified build system. The speaker illustrates the complexity of C build systems with LibPNG, which requires multiple tools and dependencies. In contrast, a Zig build system is self-contained and only requires the Zig compiler, which also serves as a C compiler using LibClang. This allows Zig to intelligently manage C compilations, dependency generation, and cross-compilation.
Zig functions as a powerful cross-compiling toolchain, shipping with header files for various LibCs and lazily building them from source. This allows for targeting different architectures and LibCs, a capability not typically found in standard C compilers. Zig also has four build modes (debug, release fast, release safe, release small) with varying levels of safety checks and optimizations, which can be mixed at the scope level.
Andrew addresses questions about Zig, explaining that all functions are potentially constant-evaluable, and if not possible, a compile error occurs. He clarifies that Zig doesn't perform dynamic memory allocation automatically and has no garbage collector, focusing on explicit memory management. When comparing Zig to Rust, he acknowledges Rust's strengths but highlights how Zig's design choices, particularly its standard library and explicit memory control, cater to different needs and prevent certain types of issues when used in environments like kernels where no default allocator can be assumed.
The speaker explains that integrating C libraries into Zig is straightforward as long as they avoid complex preprocessor macros. He confirms that adding a new error to an error set is considered a breaking change. Regarding memory safeguards, Zig distinguishes between pointers to single items and slices (pointer + length), enabling bounds checks in debug and release safe modes. Zig also avoids an 'unsafe' block concept, instead having inherently safe and unsafe operations, and plans to introduce a debug allocator to catch memory problems like leaks and use-after-free.