Yes, arrays are another distinction: - an array [3]u8 - a single item non-nullable pointer *u8 - a single item nullable pointer ?*u8 - a multi-item non-null

Yes, arrays are another distinction: - an array [3]u8 - a single item non-nullable pointer *u8 - a single item nullable pointer ?*u8 - a multi-item non-nullable pointer [*]u8 - a multi-item nullable pointer ?[*]u8 - a slice []u8 Typically your API is just made up of slices and non-nullable single item pointers. Arrays are just the typical backing store for a slice, that you might define in main or for small scratch buffers. Here's a typical example of an OS read (where the fd has been set to non-blocking already): fn readUpTo32Bytes(fd: std.os.fd_t) ![]u8 { var array: [32]u8 = undefined; var data = array[0..]; // slice of entire array data.len = std.os.read(fd, data) catch |err| switch (err) { error.WouldBlock => 0, else => return err, }; handle(data); } fn handle(data: []const u8) void { ... } If you don't need to handle EAGAIN/error.WouldBlock, then just do `data.len = try std.os.read(fd, data);` I didn't explain the `!` in the `![]u8` return type, but it's basically saying "an error or a []u8", where it's compile time known what the full set of errors is (in this case every error std.os.read can return, minus WouldBlock).