≡ Lax.C++

Non-strict template metaprogramming primitives for C++.

See synopsis.hpp for the API.

≡ Contents

• Legend
• Glossary
  • Currying
  • Meta expression
  • Meta function
  • Meta value
  • Non-strict evaluation
• Motivation
• References

≡ Legend

• _m meta expression template
• _c meta value or meta value template
• _p primitive (internal type alias or meta expression template or class)
• _t type alias (from C++11)
• _v value constexpr (from C++17)

≡ Glossary

≡ Currying

≡ Meta expression

A lax meta expression is a type that is a subtype of a single meta value and includes no other members aside from those defined by that meta value.

using a_meta_expression = add_m<auto_c<1>, auto_c<2>>;
struct also_a_meta_expression : a_meta_expression {};

Lax meta expression templates are typically curried and produce meta functions when partially applied.

≡ Meta function

A lax meta function is a meta value that has a static arity constant and an inner type template template_m that takes at least arity types as arguments and whose result is a meta expression.

struct a_meta_function_c {
  using eval = a_meta_function_c;
  static constexpr size_t arity = N;
  template <class Actual_1, ..., class Actual_N>
  struct template_m : a_meta_expression {};
};

Lax higher-order meta functions take meta functions as arguments and use them via the apply_m meta expression template. Note that template_m need not support currying like meta expression templates, because apply_m takes care of that.

≡ Meta value

A lax meta value is a meta expression whose inner eval type is an alias for the meta expression itself.

struct a_meta_value_c {
  using eval = a_meta_value_c;
  // and additional members depending on value
};

Meta values also typically include additional static constants, types, or type templates.

≡ Non-strict evaluation

≡ Motivation

≡ References