Slides against P2971R3
No implication for C++

Document number:: P3736R0
Date:: 2025-06-27
Audience:: EWG
Project:: ISO/IEC 14882 Programming Languages — C++, ISO/IEC JTC1/SC22/WG21
Reply-To:: Jan Schultke <janschultke@gmail.com>
Source:: github.com/Eisenwave/cpp-proposals/blob/master/src/implication-slides.cow

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No implication for C++
P2971R3

Jan Schultke | Slides against P2971R3 — No implication for C++ | EWG at Sofia 2025 | Slide 1

Status quo	P29271R3
// from P2971R3: reference_type<D> \|\| destructible_type<D>; not x.has_value() \|\| x == y; // Mine: p == nullptr \|\| p->valid;	// from P2971R3: nonreference_type<D> => destructible_type<D>; x.has_value() => x == y; // Mine: p != nullptr => p->valid;

Jan Schultke | Slides against P2971R3 — No implication for C++ | EWG at Sofia 2025 | Slide 2

more ways to express same code
operator precedence rules to learn
teaching materials, compilers, tooling, etc.
valuable syntax space is lost forever
- especially '=>' could be used in the future (abbreviated lambdas?)
smaller common subset with other languages
unlike ||, &&, and !, no or, and, and not
- not realistic to add implies/impl alt. keyword

Jan Schultke | Slides against P2971R3 — No implication for C++ | EWG at Sofia 2025 | Slide 3

Given (args => ...):

for one-element pack, equivalent to true => args
- suggests that neutral element is true
for zero-element pack, equivalent to false
- suggested by author for symmetry with or

This is not a problem worth solving. and and or do this much better already!

Jan Schultke | Slides against P2971R3 — No implication for C++ | EWG at Sofia 2025 | Slide 4

is equal or greater to

…

or is it?

for

(

int

;

)

{

…

}

Jan Schultke | Slides against P2971R3 — No implication for C++ | EWG at Sofia 2025 | Slide 5