No idea why the author thinks it's impossible. I mean, C stdlib comes with qsort. Here's a map in C void *map(void *in, void (*f)(void *src, void *dst), s

No idea why the author thinks it's impossible. I mean, C stdlib comes with qsort. Here's a map in C void *map(void *in, void (*f)(void *src, void *dst), size_t size, size_t in_s, size_t out_s) { void *out = malloc(size * out_s); for(size_t i = 0; i < size; i++) f(in + (i * in_s), out + (i * out_s)); return out; }