The Bedrock of Software Design

4 hours ago

Algebraic data types (ADTs) consist of product types (combining fields) and sum types (one of several variants), with sum types being especially powerful.
ADTs encode domain rules into the type system, making invalid states unrepresentable and eliminating the need for fragile comments or validation.
Sum types like Rust's Result explicitly include expected failures in function signatures, ensuring callers handle errors without surprise exceptions.
Option type models optional values, removing null/undefined ambiguity and forcing handling of absence.
Exhaustive pattern matching ensures all possible cases are covered, preventing forgotten branches and making code safer.
When domain models change, exhaustive matching on sum types causes compile errors at every affected location, guiding safe updates.
Pattern matching reduces mental overhead by letting developers focus on one case at a time while the compiler tracks all combinations.
Good domain modeling with ADTs means impossible combinations are reflected in the type system, not left as runtime concerns.

Functional programming in hica emphasizes composing functions rather than changing state, with everything as an expression.
Immutability is default using 'let'; mutation uses 'var' locally, promoting pure functions without side effects.
Functions are first-class values, supporting higher-order functions, closures, and combinators like map, filter, and fold.

Consistent data notation across code, logs, debug, and UIs reduces mental load and improves productivity.
Clojure's edn syntax provides a roundtrip property (read-print) that makes textual representation a direct mental model for data.
Separating read from eval (like JSON.parse vs eval) ensures safety and enables language-independent data exchange.

Zig supports tagged unions with compiler-enforced exhaustive switch handling, preventing bugs when new cases are added.
Working with a subset of a tagged union often requires a catch-all or listing all ignored cases, losing compiler safety or being verbose.
A real-world example: Ghostty keybind actions need to separate app-wide actions from terminal-specific actions without losing exhaustiveness.

The article extends the toy optimizer with type-based alias analysis (TBAA) to improve load-store forwarding by distinguishing memory accesses based on object types.
A hierarchical heap representation is used, where each type (e.g., Array, String) is assigned a range of integers based on pre-order and post-order tree traversal, enabling quick overlap checks.
The alias check uses range overlap: if two objects' types have overlapping ranges, they may alias; otherwise, they do not. Defaulting to 'Any' when type info is absent.

The article presents a type-safe generic data structure technique in C using unions and macros, avoiding void* and multiple #include approaches.
A union with a 'payload' member enforces type safety at compile time, catching errors when adding wrong types to structures like linked lists.
Flexible Array Members (FAM) solve memory and performance issues of void* by storing data within nodes, reducing allocations and cache misses.

Functional programming in hica emphasizes composing functions rather than changing state, with everything as an expression.
Immutability is default using 'let'; mutation uses 'var' locally, promoting pure functions without side effects.
Functions are first-class values, supporting higher-order functions, closures, and combinators like map, filter, and fold.

Consistent data notation across code, logs, debug, and UIs reduces mental load and improves productivity.
Clojure's edn syntax provides a roundtrip property (read-print) that makes textual representation a direct mental model for data.
Separating read from eval (like JSON.parse vs eval) ensures safety and enables language-independent data exchange.

Zig supports tagged unions with compiler-enforced exhaustive switch handling, preventing bugs when new cases are added.
Working with a subset of a tagged union often requires a catch-all or listing all ignored cases, losing compiler safety or being verbose.
A real-world example: Ghostty keybind actions need to separate app-wide actions from terminal-specific actions without losing exhaustiveness.

The article extends the toy optimizer with type-based alias analysis (TBAA) to improve load-store forwarding by distinguishing memory accesses based on object types.
A hierarchical heap representation is used, where each type (e.g., Array, String) is assigned a range of integers based on pre-order and post-order tree traversal, enabling quick overlap checks.
The alias check uses range overlap: if two objects' types have overlapping ranges, they may alias; otherwise, they do not. Defaulting to 'Any' when type info is absent.

The article presents a type-safe generic data structure technique in C using unions and macros, avoiding void* and multiple #include approaches.
A union with a 'payload' member enforces type safety at compile time, catching errors when adding wrong types to structures like linked lists.
Flexible Array Members (FAM) solve memory and performance issues of void* by storing data within nodes, reducing allocations and cache misses.

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