As with the others, I'll strongly disagree and chime in with a few examples off the top of my head: - ITensors.jl : They started moving from a C++ to Julia a c

As with the others, I'll strongly disagree and chime in with a few examples off the top of my head: - ITensors.jl : They started moving from a C++ to Julia a couple years ago and now their webpage doesn't even mention their original C++ implementation on its homepage anymore https://itensor.org/ https://itensor.org/ - DifferentialEquations.jl : This has many state of the art differentiatial equation solving facilities in it, many of which are improvements over old Fortran libraries. - SpecialFunctions.jl, Julia's own libm, Bessels.jl, SLEEFPirates.jl : Many core math functions have ancient Fortran or C implementations from OpenLibm or whatever, and they're being progressively replaced with better, faster versions written in pure julia that outperform the old versions.