Roadmap - Patternia
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Roadmap

This page tracks API direction and current implementation status.

Status labels: - FINISHED: already shipped and documented. - WIP: currently being designed or prepared. - NEXT: future consideration, not yet committed.

FINISHED

Completed in v0.9.2:

  • any(ps...), all(ps...) pattern combinators with OR/AND semantics.

Completed in v0.9.1:

  • val<V> static literal entry point.
  • C++20 floating-point static literals through val<V>.
  • Canonical structural entry has<...> (factory-style has<...>() removed from public API).

WIP

Current workstream for upcoming releases.

neg(p) — negation pattern

Invert the result of a sub-pattern.

match(x) | on(
  neg(val<0>) >> "non-zero",
  _ >> "zero"
);

pred(callable) — predicate pattern

Lift an arbitrary unary predicate into a first-class pattern, evaluated during the match phase rather than as a post-bind guard.

match(x) | on(
  pred([](int v) { return v % 2 == 0; }) >> "even",
  _ >> "odd"
);

NEXT

Potential follow-up items after current WIP scope is stabilized.

some / none — std::optional patterns

Dedicated patterns for the two states of std::optional.

std::optional<int> v = 42;
match(v) | on(
  $(some) >> [](int x) { return x; },
  none >> 0
);

Design Principles for New API

  • Stateless compile-time patterns should be variable templates, not function templates that return default-constructed objects.
  • Function template forms are reserved for patterns that require runtime arguments (e.g., lit(value), lit_ci(value), rng(lo, hi)).
  • Names should be short, lowercase, and read naturally in the DSL.