From Jason Turner

[optional.monadic]

C++23 → Trunk 3.8 KB 36 lines
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  1. tmp/tmp1b4_cryn/{from.md → to.md} +16 -16
tmp/tmp1b4_cryn/{from.md → to.md} RENAMED
@@ -3,96 +3,96 @@
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  ``` cpp
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  template<class F> constexpr auto and_then(F&& f) &;
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  template<class F> constexpr auto and_then(F&& f) const &;
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  ```
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- Let `U` be `invoke_result_t<F, decltype(value())>`.
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  *Mandates:* `remove_cvref_t<U>` is a specialization of `optional`.
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  *Effects:* Equivalent to:
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  ``` cpp
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  if (*this) {
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- return invoke(std::forward<F>(f), value());
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  } else {
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  return remove_cvref_t<U>();
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  }
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  ```
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  ``` cpp
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  template<class F> constexpr auto and_then(F&& f) &&;
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  template<class F> constexpr auto and_then(F&& f) const &&;
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  ```
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- Let `U` be `invoke_result_t<F, decltype(std::move(value()))>`.
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  *Mandates:* `remove_cvref_t<U>` is a specialization of `optional`.
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  *Effects:* Equivalent to:
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  ``` cpp
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  if (*this) {
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- return invoke(std::forward<F>(f), std::move(value()));
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  } else {
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  return remove_cvref_t<U>();
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  }
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  ```
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  ``` cpp
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  template<class F> constexpr auto transform(F&& f) &;
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  template<class F> constexpr auto transform(F&& f) const &;
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  ```
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- Let `U` be `remove_cv_t<invoke_result_t<F, decltype(value())>>`.
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- *Mandates:* `U` is a non-array object type other than `in_place_t` or
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- `nullopt_t`. The declaration
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  ``` cpp
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- U u(invoke(std::forward<F>(f), value()));
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  ```
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  is well-formed for some invented variable `u`.
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  [*Note 1*: There is no requirement that `U` is
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  movable [[dcl.init.general]]. — *end note*]
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  *Returns:* If `*this` contains a value, an `optional<U>` object whose
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  contained value is direct-non-list-initialized with
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- `invoke(std::forward<F>(f), value())`; otherwise, `optional<U>()`.
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  ``` cpp
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  template<class F> constexpr auto transform(F&& f) &&;
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  template<class F> constexpr auto transform(F&& f) const &&;
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  ```
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  Let `U` be
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- `remove_cv_t<invoke_result_t<F, decltype(std::move(value()))>>`.
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- *Mandates:* `U` is a non-array object type other than `in_place_t` or
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- `nullopt_t`. The declaration
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  ``` cpp
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- U u(invoke(std::forward<F>(f), std::move(value())));
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  ```
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  is well-formed for some invented variable `u`.
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  [*Note 2*: There is no requirement that `U` is
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  movable [[dcl.init.general]]. — *end note*]
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  *Returns:* If `*this` contains a value, an `optional<U>` object whose
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  contained value is direct-non-list-initialized with
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- `invoke(std::forward<F>(f), std::move(value()))`; otherwise,
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  `optional<U>()`.
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  ``` cpp
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  template<class F> constexpr optional or_else(F&& f) const &;
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  ```
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- *Constraints:* `F` models `invocable<>` and `T` models
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  `copy_constructible`.
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  *Mandates:* `is_same_v<remove_cvref_t<invoke_result_t<F>>, optional>` is
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  `true`.
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@@ -108,11 +108,11 @@ if (*this) {
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  ``` cpp
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  template<class F> constexpr optional or_else(F&& f) &&;
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  ```
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- *Constraints:* `F` models `invocable<>` and `T` models
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  `move_constructible`.
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  *Mandates:* `is_same_v<remove_cvref_t<invoke_result_t<F>>, optional>` is
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  `true`.
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  ``` cpp
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  template<class F> constexpr auto and_then(F&& f) &;
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  template<class F> constexpr auto and_then(F&& f) const &;
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  ```
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+ Let `U` be `invoke_result_t<F, decltype(*`*`val`*`)>`.
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  *Mandates:* `remove_cvref_t<U>` is a specialization of `optional`.
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  *Effects:* Equivalent to:
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  ``` cpp
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  if (*this) {
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+ return invoke(std::forward<F>(f), *val);
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  } else {
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  return remove_cvref_t<U>();
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  }
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  ```
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  ``` cpp
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  template<class F> constexpr auto and_then(F&& f) &&;
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  template<class F> constexpr auto and_then(F&& f) const &&;
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  ```
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+ Let `U` be `invoke_result_t<F, decltype(std::move(*`*`val`*`))>`.
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  *Mandates:* `remove_cvref_t<U>` is a specialization of `optional`.
30
 
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  *Effects:* Equivalent to:
32
 
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  ``` cpp
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  if (*this) {
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+ return invoke(std::forward<F>(f), std::move(*val));
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  } else {
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  return remove_cvref_t<U>();
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  }
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  ```
40
 
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  ``` cpp
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  template<class F> constexpr auto transform(F&& f) &;
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  template<class F> constexpr auto transform(F&& f) const &;
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  ```
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+ Let `U` be `remove_cv_t<invoke_result_t<F, decltype(*`*`val`*`)>>`.
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+ *Mandates:* `U` is a valid contained type for `optional`. The
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+ declaration
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  ``` cpp
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+ U u(invoke(std::forward<F>(f), *val));
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  ```
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  is well-formed for some invented variable `u`.
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  [*Note 1*: There is no requirement that `U` is
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  movable [[dcl.init.general]]. — *end note*]
59
 
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  *Returns:* If `*this` contains a value, an `optional<U>` object whose
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  contained value is direct-non-list-initialized with
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+ `invoke(std::forward<F>(f), *`*`val`*`)`; otherwise, `optional<U>()`.
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  ``` cpp
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  template<class F> constexpr auto transform(F&& f) &&;
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  template<class F> constexpr auto transform(F&& f) const &&;
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  ```
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  Let `U` be
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+ `remove_cv_t<invoke_result_t<F, decltype(std::move(*`*`val`*`))>>`.
71
 
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+ *Mandates:* `U` is a valid contained type for `optional`. The
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+ declaration
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  ``` cpp
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+ U u(invoke(std::forward<F>(f), std::move(*val)));
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  ```
78
 
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  is well-formed for some invented variable `u`.
80
 
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  [*Note 2*: There is no requirement that `U` is
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  movable [[dcl.init.general]]. — *end note*]
83
 
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  *Returns:* If `*this` contains a value, an `optional<U>` object whose
85
  contained value is direct-non-list-initialized with
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+ `invoke(std::forward<F>(f), std::move(*`*`val`*`))`; otherwise,
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  `optional<U>()`.
88
 
89
  ``` cpp
90
  template<class F> constexpr optional or_else(F&& f) const &;
91
  ```
92
 
93
+ *Constraints:* `F` models `invocable` and `T` models
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  `copy_constructible`.
95
 
96
  *Mandates:* `is_same_v<remove_cvref_t<invoke_result_t<F>>, optional>` is
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  `true`.
98
 
 
108
 
109
  ``` cpp
110
  template<class F> constexpr optional or_else(F&& f) &&;
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  ```
112
 
113
+ *Constraints:* `F` models `invocable` and `T` models
114
  `move_constructible`.
115
 
116
  *Mandates:* `is_same_v<remove_cvref_t<invoke_result_t<F>>, optional>` is
117
  `true`.
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