How exactly are Julia Arrays Implemented?

mbauman · January 5, 2023, 6:26pm

In C:

JuliaLang/julia/blob/321c5f55165643cff299ae7d270cfb3d5df73779/src/julia.h#L172-L189


      
          JL_EXTENSION typedef struct {
              JL_DATA_TYPE
              void *data;
              size_t length;
              jl_array_flags_t flags;
              uint16_t elsize;  // element size including alignment (dim 1 memory stride)
              uint32_t offset;  // for 1-d only. does not need to get big.
              size_t nrows;
              union {
                  // 1d
                  size_t maxsize;
                  // Nd
                  size_t ncols;
              };
              // other dim sizes go here for ndims > 2
          
          
    // followed by alignment padding and inline data, or owner pointer
          } jl_array_t;

See also: What is special about Array, String, and Symbol?