a perhaps primitive compile-time symbolic computation library. Would be great to extend this further.

Can find what is in here from Vincent Reverdy's CppCon 2023 presentation Symbolic Calculus for High-performance Computing From Scratch Using C++23, a pdf of which is contained in this repository. Here is a link to the YouTube video. So far I have personally added very little, despite it being quite extensible from the start.

If paired with a library like gcem will allow use for this entirely at compile time, that is, compile within constexpr and consteval contexts. Here is a working example linked with gcem. The code here uses the Standard Library, so until C++26 (or later), constexpr will not compile with certain expressions; but switching between using std math or gcem math is a matter of replacing std:: by gcem::, so if you feel like making the switch it's immediate – check out the example on godbolt...

At the end of the slides are some exercises for the reader...

Partial substitution

• for now only full substitution works
• partial substitution needs more work: e.g. f(a = 5.0, w = 2.5) should generate a new formula

Rewriting

• Replacing terms by others (rewriting) need also more work: f(x = y / z) should generate a new formula
• Simplification based on mathematical concepts
• Symbolic calculus (derivatives, integrals)
• Full blown custom rule-based rewriting

Again, would love to grow this seed.

Really this is a matter of compiling with the -std=c++23 flag, but since import std; finally works in Clang 18 and GCC 15, and with (experimental) cmake support, symbols now comes as a module and builds with module std. It's less steps to just compile it on the command line but apparently there are other preferences out there.

First of all grab a copy:

git clone www.github.com/colinrford/symbols
cd symbols

then, in the directory symbols

mkdir build && cd build
cmake .. -DCMAKE_CXX_COMPILER=/path/to/your/modern/compiler -G Ninja

and so long as this succeeds, run

ninja

the only file that is created at this time (May 2, 2025; September 15, 2025) is the test_symbol program in tests directory. test_symbol does not do much besides compute a basic expression.

Please excuse any CMake shortcomings, I will try to catch any and fix accordingly.

More interesting examples on the way.