The CDS is releasing a new HEALPix library implemented in Java. Before possibly porting it in C, we are experimenting with the Rust programming language. It allows the library to be compiled into WebAssembly or native code, and thus to easily plug it into web browsers, Python codes or PostgreSQL, to name but a few. The library is distributed under the 3-clause BSD licence. It focuses on our own needs, on performances and accuracy. We are investigating the potential usage of the WebAssembly version into Aladin Lite. The objective is twofold: supporting deeper orders (up to 24, the present limit being 13), and changing the current GPL license to a less restrictive one. Aladin desktop has already started to resort to the Java version. Unlike the ``official'' library, coming from the cosmology community, our Java version do not currently supports Spherical Fourier Transformations and do not support the RING scheme (also it is able to transform cells numbers from the nested scheme to the ring scheme and vice-versa). In return, it do support additional features like: distinguishing between cells partially and fully overlapped by a cone; exact cells-overlapped-by-cone solution; very-fast approximate cells-overlapped-by-cone function dedicated to cross-matches; supporting self-intersecting polygons of any size; fast ordered list of small cells surrounding a larger cell; MOC support in cells-overlapped-by-cone queries; BMOC support (MOC storing an additional flag for each cell); etc.
Link to PDF (may not be available yet): P13-13.pdf