C++--

C++ to C transpiler

Example

main.cpp:

#include <iostream>
int main() {
    std::cout << "Hello, world!" << std::endl;
}

$ poetry build
$ pip install dist/cppmm-0.1.0-py3-none-any.whl
$ c++-- main.cpp -o main.c
$ gcc main.c -o main -lstdc++
$ ./main
Hello, World!

Proof of correctness

Let

• CPP ::= all valid C++ programs
• C ::= all valid C programs
• (p1 : CPP) ≅ (p2 : C) ::= p1 and p2 are semantically equivalent
• [[p : CPP]] : C ::= the interpretation of p under C++--

Then

	Judgement	Evidence
1	C++-- can't possibly work (i.e. ∀ (p : CPP), p ≇ [[p]])	Assumption
2	p1 ≇ [[p1]] → (p1 ≅ [[p1]] → ∀ (p : CPP), p ≅ [[p]])	by Principal of Explosion
3	p1 ≇ [[p1]]	by (1) and ∀-elim
4	p1 ≅ [[p1]] → ∀ (p : CPP), p ≅ [[p]]	by (2), (3), Modus Ponens
5	(∃ (p1 : CPP), p1 ≅ [[p1]]) → ∀ (p : CPP), p ≅ [[p]]	by (4) and ∃-elim
6	(∃ (p : CPP), p ≅ [[p]]) → ∀ (p : CPP), p ≅ [[p]]	by (5) and ɑ-equiv
7	C++-- works for hello_world.cpp above (i.e. ∃ (p : CPP), p ≅ [[p]])	Inspection
8	∀ (p : CPP), p ≅ [[p]]	by (6), (7), Modus Ponens