Here's an excerpt from std.ArrayList[1]: pub fn ArrayList(comptime T: type) type { return struct { const Self = @This(); r

Here's an excerpt from std.ArrayList[1]: pub fn ArrayList(comptime T: type) type { return struct { const Self = @This(); raw_items: []T, len: usize, allocator: *Allocator, // ... pub fn append(self: *Self, item: T) !void { const new_item_ptr = try self.addOne(); new_item_ptr.* = item; } pub fn addOne(self: *Self) !*T { const new_length = self.len + 1; try self.ensureCapacity(new_length); return self.addOneAssumeCapacity(); } // ... }; } test "std.ArrayList.basic" { var bytes: [1024]u8 = undefined; const allocator = &std.heap.FixedBufferAllocator.init(bytes[0..]).allocator; var list = ArrayList(i32).init(allocator); try list.append(1); try list.append(2); try list.append(3); assert(list.len == 3); } In summary, functions that can fail have an inferred error set, or an explicit one[2]. At the callsite of functions that can fail will either be `if`, `while`, `catch`, or `try`, in order to deal with the error case. [1]: https://github.com/ziglang/zig/blob/e3d8cae35a5d194386eacd9afa4f496111a37e16/std/array_list.zig https://github.com/ziglang/zig/blob/e3d8cae35a5d194386eacd9a... [2]: https://ziglang.org/documentation/master/#Error-Set-Type https://ziglang.org/documentation/master/#Error-Set-Type